Multilingual Dictionary MCP

An offline-first MCP server for multilingual dictionary lookups — definitions, synonyms, antonyms, hypernyms, hyponyms, meronyms, translations, etymology, pronunciation, semantic neighbors, rhymes, and more — across 4,755 languages.

No third-party APIs. No rate limits. No outages. The server downloads its data from a CDN once on first run and never goes online again.

What's bundled

Source	Size	What it covers
Wiktextract (Kaikki.org)	6.6 GB	10.5M dictionary entries across 4,755 languages — definitions, etymology, IPA, translations
ConceptNet 5.7	5.6 GB	24.3M semantic edges across 80+ languages — Synonym, Antonym, IsA, PartOf, RelatedTo, UsedFor, CapableOf, AtLocation, DerivedFrom, EtymologicallyRelatedTo
Numberbatch embeddings	3 GB	9.16M concepts × 300d multilingual embeddings — semantic neighbors via cosine similarity
CMU Pronouncing Dictionary	19 MB	English rhymes, soundalikes, autocomplete, spell patterns

Total bundle: ~21 GB (medium profile, default).

One bundle, one download

The whole bundle ships in 6 artifacts. Total 5.4 GB on the wire (gzip-compressed where it helps), 15.6 GB on disk after extraction. Everything downloads on first run; no profiles, no opt-ins.

Installation

npm install -g multilingual-dictionary-mcp

Claude Desktop / Claude Code

{
  "mcpServers": {
    "multilingual-dictionary": {
      "command": "npx",
      "args": ["-y", "multilingual-dictionary-mcp"]
    }
  }
}

On first run, the server downloads its data bundle (~5.4 GB compressed → ~15.6 GB on disk) from multilingual-dictionary-mcp-data.nyc3.cdn.digitaloceanspaces.com into ~/.cache/multilingual-dictionary-mcp/ (overridable via MDM_DATA_DIR). Each artifact is gzip-decompressed during the stream and must match the SHA-256 and size pinned in the package (src/data/pinned.ts); the data host's own manifest is not trusted, and anything that doesn't match is refused. A complete local cache is used as-is without contacting the host, so an unreachable host never affects an existing install. Subsequent runs are instant.

Tools

Multilingual word relations (ConceptNet — 80+ languages)

dictionary_synonyms, dictionary_antonyms, dictionary_hypernyms, dictionary_hyponyms, dictionary_meronyms, dictionary_holonyms, dictionary_derived_from, dictionary_etymologically_related, dictionary_used_for, dictionary_capable_of, dictionary_at_location, dictionary_translate, dictionary_all_relations

Embedding-based semantic search (Numberbatch — 78 languages)

Tool	What it does
`dictionary_related`	Semantic neighbors via cosine similarity — much denser than ConceptNet RelatedTo
`dictionary_semantic_neighbors`	Explicit embedding lookup with optional cross-lingual filter
`dictionary_means_like`	Multilingual "means approximately" via Numberbatch (works in any of the 78 covered languages)

Definitions & etymology (Wiktextract — 4,755 languages)

Tool	What it does
`dictionary_lookup`	Definitions + IPA + etymology grouped by language
`dictionary_summary`	Concatenated short definition
`dictionary_etymology`	Etymology text
`dictionary_pronunciation`	IPA pronunciations
`dictionary_search`	Prefix-search the corpus
`dictionary_random`	Random word entry

English-specific (CMU Pronouncing Dictionary)

Tool	What it does
`dictionary_rhymes`	Perfect or near rhymes
`dictionary_sounds_like`	Homophones / soundalikes
`dictionary_spelled_like`	Spelling pattern (`?` and `*` wildcards)
`dictionary_suggest`	Autocomplete prefix

Examples

> What are the synonyms of "feliz" in Spanish?
[uses dictionary_synonyms with language: "es"]

> Translate "happiness" into Hebrew
[uses dictionary_translate with language: "en", targetLanguage: "he"]

> What's the etymology of "serendipity"?
[uses dictionary_etymology]

> Find words semantically similar to "café" across languages
[uses dictionary_semantic_neighbors]

> What rhymes with "orange"?
[uses dictionary_rhymes with perfect: false]

Development

npm install
npm run build
npm test           # all tests run without local data or network

Source layout:

src/
├── index.ts            # MCP server entry, blocks on first-run install
├── data/
│   ├── paths.ts        # CDN base, profile selection, data dir
│   ├── installer.ts    # First-run downloader + SHA-256 verification
│   └── local-store.ts  # SQLite + Numberbatch matrix wrappers
└── tools/
    ├── relations.ts    # 13 ConceptNet relation tools + 1 embedding tool
    ├── definitions.ts  # 6 Wiktextract definition tools
    └── english.ts      # 5 CMU dict + Numberbatch tools

Total: 24 tools.

Building the data bundle yourself

The CDN ships official builds, but the entire pipeline is in data-pipeline/ — see its README. You can rebuild from upstream sources, ship to your own bucket, and override MDM_CDN_BASE. A mirror of the official bundle works as is. A bundle you rebuilt yourself has different hashes, so also update src/data/pinned.ts to match your manifest.json in your build.

CI / Release

CI runs build + tests on Node 20 & 22 for every push and PR.
Publish runs on GitHub Release publish, pushes to npm and GitHub Packages.

multilingual-dictionary-mcp