# Merriam-Webster API

> Merriam-Webster returns dictionary definitions, thesaurus data, and Word of the Day entries as a workflow and API.

Merriam-Webster (MW) Define word returns pronunciation, definitions, examples, and word history for a word or phrase you provide. Get synonyms returns meanings, synonyms, antonyms, and related words for a word you provide. Get word of the day returns a word, meaning, pronunciation, example, and background note; provide a date for an archive entry or omit it for today.

- Page: https://fous.com/tools/merriam-webster
- Handle: `@merriam-webster`
- Category: [Education](https://fous.com/tools/category/education)
- Source website: https://merriam-webster.com
- Last verified: Sep 30, 2026

## Methods

### Define word

Operation `define_word`, version 1. 1 credit per completed call. Failed calls without a completed billing receipt are free; completed work can remain charged if delivery is interrupted.

Look up a word or phrase in Merriam-Webster’s dictionary and return pronunciation, meanings, examples, and word history. Only publicly listed dictionary entries are included.

**Input**

| Field | Type | Required | Example | Description |
|---|---|---|---|---|
| `word` | string | yes | `"run"` | The word or phrase to look up, for example serendipity. |

**Input schema**

```json
{
  "type": "object",
  "required": [
    "word"
  ],
  "properties": {
    "word": {
      "type": "string",
      "description": "The word or phrase to look up, for example serendipity.",
      "examples": [
        "run",
        "serendipity"
      ]
    }
  },
  "additionalProperties": false,
  "examples": [
    {
      "word": "run"
    },
    {
      "word": "serendipity"
    }
  ]
}
```

**Output**

| Field | Type | Example | Description |
|---|---|---|---|
| `word` | string | `"run"` | Dictionary headword. |
| `entries` | array |  | Dictionary entries in page order. |
| `entries[].etymology` | string or null | `"Middle English ronnen, alteration of rinnen, intransitive verb (from Old English iernan, rinnan & Old Norse rinna ) & o` |  |
| `entries[].definitions` | array |  | Numbered definitions in displayed order. |
| `entries[].part_of_speech` | string | `"verb"` |  |
| `entries[].first_known_use` | string or null | `"before the 12th century"` |  |
| `entries[].example_sentences` | array |  |  |
| `pronunciation` | string or null | `"ˈrən"` | Pronunciation shown for the headword. |
| `merriam_webster_link` | string | `"https://www.merriam-webster.com/dictionary/run"` | Page for this dictionary word. |
| `pronunciation_audio_link` | string or null | `"https://media.merriam-webster.com/audio/prons/en/us/mp3/r/run00001.mp3"` | Link to the pronunciation audio when available. |

**Example input**

```json
{
  "word": "run"
}
```

**Example output**

```json
{
  "word": "run",
  "entries": [
    {
      "etymology": "Middle English ronnen, alteration of rinnen, intransitive verb (from Old English iernan, rinnan & Old Norse rinna ) & of rennen, transitive verb, from Old Norse renna; akin to Old High German rinnan, …",
      "definitions": [
        "intransitive verb 1a. to go faster than a walk",
        "intransitive verb 1a. specifically: to go steadily by springing steps so that both feet leave the ground for an instant in each step"
      ],
      "part_of_speech": "verb",
      "first_known_use": "before the 12th century",
      "example_sentences": [
        "When they heard the alarm ring, they ran.",
        "let chickens run loose"
      ]
    },
    {
      "etymology": null,
      "definitions": [
        "1a. an act or the action of running : continued rapid movement",
        "1b. a quickened gallop"
      ],
      "part_of_speech": "noun",
      "first_known_use": "15th century",
      "example_sentences": [
        "goes out for a run every morning",
        "When the robbers heard the alarm, they made a run for it. [=they ran away to avoid capture]"
      ]
    }
  ],
  "pronunciation": "ˈrən",
  "merriam_webster_link": "https://www.merriam-webster.com/dictionary/run",
  "pronunciation_audio_link": "https://media.merriam-webster.com/audio/prons/en/us/mp3/r/run00001.mp3"
}
```

### Get synonyms

Operation `get_synonyms`, version 1. 1 credit per completed call. Failed calls without a completed billing receipt are free; completed work can remain charged if delivery is interrupted.

Get a word’s thesaurus meanings, examples, synonyms, antonyms, and related words from its public Merriam-Webster page.

**Input**

| Field | Type | Required | Example | Description |
|---|---|---|---|---|
| `word` | string | yes | `"happy"` | A word to look up in the thesaurus, for example happy. |

**Input schema**

```json
{
  "type": "object",
  "required": [
    "word"
  ],
  "properties": {
    "word": {
      "type": "string",
      "minLength": 1,
      "description": "A word to look up in the thesaurus, for example happy.",
      "examples": [
        "happy",
        "light"
      ]
    }
  },
  "additionalProperties": false,
  "examples": [
    {
      "word": "happy"
    },
    {
      "word": "light"
    }
  ]
}
```

**Output**

| Field | Type | Example | Description |
|---|---|---|---|
| `word` | string | `"happy"` | The word shown on the thesaurus page. |
| `meanings` | array |  | Meanings in the order they appear on the page. Similar words appear under synonyms; related words are included only when shown separately. |
| `meanings[].meaning` | string | `"experiencing pleasure, satisfaction, or delight"` |  |
| `meanings[].antonyms` | array |  |  |
| `meanings[].synonyms` | array |  |  |
| `meanings[].page_link` | string | `"https://www.merriam-webster.com/thesaurus/happy#thesaurus-entry-1-1"` |  |
| `meanings[].related_words` | array |  |  |
| `meanings[].part_of_speech` | string | `"adjective"` |  |
| `meanings[].example_sentence` | string or null | `"made bread for the first time and was happy with the tasty result"` |  |
| `thesaurus_link` | string | `"https://www.merriam-webster.com/thesaurus/happy"` | Link to the word’s thesaurus page. |

**Example input**

```json
{
  "word": "happy"
}
```

**Example output**

```json
{
  "word": "happy",
  "meanings": [
    {
      "meaning": "experiencing pleasure, satisfaction, or delight",
      "antonyms": [
        "unhappy",
        "sad",
        "dissatisfied"
      ],
      "synonyms": [
        "delighted",
        "pleased",
        "glad"
      ],
      "page_link": "https://www.merriam-webster.com/thesaurus/happy#thesaurus-entry-1-1",
      "related_words": [],
      "part_of_speech": "adjective",
      "example_sentence": "made bread for the first time and was happy with the tasty result"
    },
    {
      "meaning": "coming or happening by good luck especially unexpectedly",
      "antonyms": [
        "unhappy",
        "unfortunate",
        "unlucky"
      ],
      "synonyms": [
        "lucky",
        "fortunate",
        "convenient"
      ],
      "page_link": "https://www.merriam-webster.com/thesaurus/happy#thesaurus-entry-1-2",
      "related_words": [],
      "part_of_speech": "adjective",
      "example_sentence": "a happy discovery, finding the letter that would prove her innocence"
    },
    {
      "meaning": "feeling that one's needs or desires have been met",
      "antonyms": [
        "unhappy",
        "dissatisfied",
        "displeased"
      ],
      "synonyms": [
        "satisfied",
        "pleased",
        "contented"
      ],
      "page_link": "https://www.merriam-webster.com/thesaurus/happy#thesaurus-entry-1-3",
      "related_words": [],
      "part_of_speech": "adjective",
      "example_sentence": "has been much happier ever since she moved"
    }
  ],
  "thesaurus_link": "https://www.merriam-webster.com/thesaurus/happy"
}
```

### Get word of the day

Operation `get_word_of_the_day`, version 1. 1 credit per completed call. Failed calls without a completed billing receipt are free; completed work can remain charged if delivery is interrupted.

Get Merriam-Webster’s Word of the Day for today or a past archive date, with its meaning, example, pronunciation, and background note. Dates without a published entry are unavailable.

**Input**

| Field | Type | Required | Example | Description |
|---|---|---|---|---|
| `date` | string | no | `"2025-02-15"` | Day to look up (YYYY-MM-DD), such as 2025-02-15. Omit for today. |

**Input schema**

```json
{
  "type": "object",
  "properties": {
    "date": {
      "type": "string",
      "format": "date",
      "description": "Day to look up (YYYY-MM-DD), such as 2025-02-15. Omit for today.",
      "examples": [
        "2025-02-15",
        "2006-08-31",
        "2026-09-15"
      ]
    }
  },
  "additionalProperties": false,
  "examples": [
    {},
    {
      "date": "2025-02-15"
    },
    {
      "date": "2006-08-31"
    }
  ]
}
```

**Output**

| Field | Type | Example | Description |
|---|---|---|---|
| `date` | string | `"2026-09-28"` | Publication date. |
| `link` | string | `"https://www.merriam-webster.com/word-of-the-day/fungible-2026-09-28"` | Word of the Day page link. |
| `word` | string | `"fungible"` | Word of the Day. |
| `definition` | string or null | `"Fungible describes things, such as currency, goods, and commodities, that can be exchanged for something else of the sa` | Meaning in plain text. |
| `did_you_know` | string or null |  | Did You Know? note in plain text. |
| `pronunciation` | string or null | `"FUN-juh-bul"` | Pronunciation shown on the page. |
| `part_of_speech` | string or null | `"adjective"` | Part of speech shown on the page. |
| `example_sentence` | string or null | `"A dollar bill is considered fungible because it can easily and acceptably be traded for ten dimes, four quarters, twent` | Usage example in plain text. |

**Example input**

```json
{}
```

**Example output**

```json
{
  "date": "2026-09-28",
  "link": "https://www.merriam-webster.com/word-of-the-day/fungible-2026-09-28",
  "word": "fungible",
  "definition": "Fungible describes things, such as currency, goods, and commodities, that can be exchanged for something else of the same kind or value. In broader usage, fungible can also mean “interchangeable,” as …",
  "did_you_know": "Before expectations about the origins of fungible mushroom into mycological fantasy: no, fungible has no relation to the noun fungus and its plural fungi. The fungi in fungible is there because of the…",
  "pronunciation": "FUN-juh-bul",
  "part_of_speech": "adjective",
  "example_sentence": "A dollar bill is considered fungible because it can easily and acceptably be traded for ten dimes, four quarters, twenty nickels, or one hundred pennies, as well as any other dollar bill."
}
```

## Quick start

Replace `YOUR_API_KEY` with a Fous API key. To create one, open Developers at the bottom of Fous Studio, turn on Developer mode, then go to API keys (https://app.fous.com/keys). Change the values in `input` to run the same tool on new data.

```bash
curl 'https://api.fous.com/v1/query' \
  --fail-with-body --silent --show-error --max-time 180 \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H 'Content-Type: application/json' \
  --data-raw '{
  "api": "@merriam-webster",
  "visibility": "public",
  "operation": "define_word",
  "version": 1,
  "input": {
    "word": "run"
  },
  "response": {
    "format": "json"
  }
}'
```

```python
# Save as fous.py and run with python3 fous.py. No packages needed.
import json
import urllib.error
import urllib.request

api_key = "YOUR_API_KEY"

body = json.loads("{\n  \"api\": \"@merriam-webster\",\n  \"visibility\": \"public\",\n  \"operation\": \"define_word\",\n  \"version\": 1,\n  \"input\": {\n    \"word\": \"run\"\n  },\n  \"response\": {\n    \"format\": \"json\"\n  }\n}")
request = urllib.request.Request(
    "https://api.fous.com/v1/query",
    data=json.dumps(body).encode("utf-8"),
    headers={
        "Authorization": f"Bearer {api_key}",
        "Content-Type": "application/json",
    },
    method="POST",
)
try:
    with urllib.request.urlopen(request, timeout=180) as response:
        result = json.load(response)
except urllib.error.HTTPError as error:
    raise RuntimeError(f"HTTP {error.code}: {error.read().decode('utf-8', errors='replace')}") from error
if result.get("success") is False:
    raise RuntimeError(result.get("error", {}).get("message", "Request failed"))
print(json.dumps(result["data"]["output"], indent=2))
```

```typescript
// Save as fous.mts and run with npx tsx fous.mts.
const apiKey = "YOUR_API_KEY";

const response = await fetch("https://api.fous.com/v1/query", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${apiKey}`,
    "Content-Type": "application/json",
  },
  signal: AbortSignal.timeout(180_000),
  body: JSON.stringify({
  "api": "@merriam-webster",
  "visibility": "public",
  "operation": "define_word",
  "version": 1,
  "input": {
    "word": "run"
  },
  "response": {
    "format": "json"
  }
}),
});
type ApiResult = { success: boolean; data?: { output: unknown }; error?: { message: string } };
const result: ApiResult = await response.json();
if (!response.ok || result.success === false) {
  throw new Error(result.error?.message ?? `HTTP ${response.status}`);
}
if (!result.data) throw new Error("Missing API response data");
console.log(result.data.output);
```

## Use from an AI assistant

Connect this tool to Claude Code, Claude Desktop, Cursor, VS Code, Codex and any MCP client as its own MCP server. Each method is a typed tool whose arguments are the method’s input.

- Server URL: `https://api.fous.com/mcp/tools/merriam-webster`
- Authorization: `Authorization: Bearer <Fous API key>`

**Tools**

- `define_word`: Define word. 1 credit per completed call. Failed calls without a completed billing receipt are free; completed work can remain charged if delivery is interrupted.
- `get_synonyms`: Get synonyms. 1 credit per completed call. Failed calls without a completed billing receipt are free; completed work can remain charged if delivery is interrupted.
- `get_word_of_the_day`: Get word of the day. 1 credit per completed call. Failed calls without a completed billing receipt are free; completed work can remain charged if delivery is interrupted.
- `fous_get_run`: the result of a run that was still going, by its `request_id`. Free.

Claude Code:

```bash
claude mcp add --scope user --transport http fous-merriam-webster https://api.fous.com/mcp/tools/merriam-webster --header "Authorization: Bearer ${FOUS_API_KEY:?Set FOUS_API_KEY to your Fous API key}"
```

To give the assistant every tool, connect `https://api.fous.com/mcp`: it finds one with `fous_search_tools` and runs it with `fous_run_tool`. Setup for other clients: https://fous.com/llms-full.txt.

## Use cases

- Check definitions and word histories while editing educational materials.
- Compare synonyms and antonyms to choose precise wording.
- Find example sentences for a word.
- Share the daily featured word with learners.
- Review archived Word of the Day entries by date.

## FAQ

### Can I run it with my own inputs?

Yes. Change the inputs in Studio and press Run, or send new inputs from your code, or ask a connected AI assistant.

### Can I call this Merriam-Webster tool as an API?

Yes. Send a POST request to /v1/query with your Fous API key and the inputs, and get JSON back.

### How much does it cost?

Each completed run costs 1 credit. Failed runs without a completed receipt are free; completed work can remain charged if delivery is interrupted. With pay as you go, a credit costs 1¢. Monthly plans cost less per credit.

### Do I need a Merriam-Webster account?

No. You only need a Fous account.

### How current is the data?

Fous gets the data from merriam-webster.com when you run it. Some results are reused for up to 24 hours, and results that use your account or key are never reused. It was last verified on Sep 30, 2026.

### What does a word mean?

Use Define word with a word or phrase to get its meanings, pronunciation, examples, and word history.

### What are synonyms or antonyms for a word?

Use Get synonyms with a word to see its meanings, synonyms, antonyms, and related words.

### What is today’s Word of the Day?

Use Get word of the day without a date for today’s entry, or provide a date for an archive entry.

## Related

- [Dictionary.com API](https://fous.com/tools/dictionary-com.md): Dictionary.com provides definitions, pronunciations, audio, examples, and word origins, plus ranked synonyms and antonyms for public Thesaurus.com entries; some word details may be unavailable.
- [Wiktionary API](https://fous.com/tools/wiktionary.md): A free, multilingual dictionary with word meanings and language information.
- [Cambridge Dictionary API](https://fous.com/tools/cambridge-dictionary.md): Cambridge Dictionary provides English definitions, examples, grammar labels, and available UK and US pronunciations, plus translations and paired examples for supported languages, reflecting details shown on its pages.
- [Urban Dictionary API](https://fous.com/tools/urban-dictionary.md): Urban Dictionary provides crowdsourced slang definitions and examples, plus up to 30 newest Words of the Day with featured dates.
- [Etymonline API](https://fous.com/tools/etymonline.md): Origins and histories of English words from the Online Etymology Dictionary.
- [WordReference API](https://fous.com/tools/wordreference.md): Dictionary translations and language reference.
- [RhymeZone API](https://fous.com/tools/rhymezone.md): RhymeZone finds rhymes, similar-sounding words, and related words, including synonyms, opposites, descriptions, and associations; some results lack relevance scores or syllable and part-of-speech details.
- [Wikipedia API](https://fous.com/tools/wikipedia.md): Wikipedia returns article summaries, images, facts, relevant search matches, readable text and daily historical events, plus human-view counts from July 2015 onward.
- [All Education tools](https://fous.com/tools/category/education)