XF English Dictionary API

Powerful and cost-efficient.
Innovative features.
Low latency.


Large dictionary

Contains over one million words and phrases, including word forms and many proper nouns. Examples, synonyms, antonyms, pronunciations (including audio) and learner-friendly word usage frequency data.

Linguistic analysis

The API processes text around the target word and determines the most appropriate dictionary entries to be displayed at top of word list. Shows phrases that the target word may be part of. You can always look up a separate word as well.

Related words

The API is capable of adding certain related words to response, helping end users better understand and learn the target word.


The XF English Dictionary contains over one million words and phrases (including many proper nouns, for example names of cities etc). By default, the API query returns word/phrase definitions, usage examples, word forms, synonyms, antonyms, pronunciations (both textual and audio), and learner-friendly word usage frequency data. You can submit either a word or arbitrary text where the target word is selected. The API breaks text into sentences, applies linguistic analysis, identifies possible root forms of the target word, and returns a list of words, most relevant results at top of the list. For example, if you submit sentence

RapidAPI is without a doubt the best API marketplace.

where doubt is the target word, linguistic analysis helps us figure out that, in this context, doubt is most likely a noun. Consequently, NOUN doubt is added to the word list before VERB. The accuracy of linguistic analysis depends on context, but it is, on average, over 90%. Note that the response also contains phrases that the target word may be part of. The XF English Dictionary often adds certain related/useful words to the response. These words may help language learners to better grasp meaning of the target word. For instance, if you submit a sentence like

RapidAPI is undoubtedly the best API marketplace.

the API will (by default) return definitions for both undoubtedly and doubt. Related words can be excluded from response by setting parameter ’relatedWords’ to ’false’.

If a proper noun is not found in the dictionary, the API may return link(s) to Wikipedia articles.

If you like the concept but prefer a different dictionary, then XF English Dictionary API framework can still be used for data preprocessing so your application can take advantage of linguistic analysis, phrase shortlisting and related words. Contact us at info@xfd.plus for more information.

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Try the API

Submit a word or sentence, e.g.

They successfully completed their project.

where successfully is the word to look up in dictionary

Note that the API will always automatically extract sentences from raw text for you.
For the sake of simplicity, this example initially consists of only one sentence.