Wordnik shows definitions from multiple sources, so you can see as many different takes on a word's meaning as possible.
We search billions of words in our phrase dictionary on how commonly used they are to identify the proper sentence structure. This helps improve the use of collocation, diction and syntax in your writing when choosing the appropriate sentence pattern. Our wording tool acts as a correct sentence structure checker, e.g. by associating correct examples of prepositions with common language usage to give you the best suggestions for the proper preposition. Our tool can help teach wording, grammar, and expressions, which helps you identify the proper word choice and word order.
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An advanced learner's dictionary with pronunciation recordings. The best one for grammar students, IMO.