Words shape how we think and communicate. These online dictionaries and thesauri will help you choose them with clarity and purpose.
One Look dictionary
You can use OneLook to find definitions, related words, quotes, names, lyrics, colours, and more.
One Look functions as a search engine and thesaurus that aggregates and indexes definitions over 1,000 different online dictionaries and other word resources.

One Look also provides options such as synonyms in different word classes (noun, verb, adjective), oldest, most formal, etc.

Emoji DB (beta)
Emoji DB (beta)
Power Thesaurus
According to its description, Power Thesaurus is community driven, user-friendly and powerful.
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Because users can vote, suggest, and refine entries, the synonyms/antonyms lists tend to reflect more natural, modern usage rather than only outdated or overly “dictionary-style” alternatives.
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There is editorial oversight to maintain quality
Rhyme Zone
Rhyme Zone is a handy tool when you need to find a rhyming word.

Rhyming words are presented according to syllables (up to 10 in most cases) so useful for poetry, song lyrics or limericks.
Merriam Webster
The Merriam Webster dictionary/thesaurus includes definitions, synonyms, trending words and slang, word of the day, example sentences, punctuation, grammar and usage, word history, rhymes, phrases containing, commonly confused and more.

Similar online dictionaries:
Oxford Learners' Dictionary
Cambridge Dictionary
Collins Dictionary