An idiom is a common word or phrase with a culturally understood meaning that differs from what its composite words' denotations would suggest. For example, an English speaker would understand the phrase "kick the bucket" to mean "to die" – and also to actually kick a bucket. Furthermore, they would understand when each meaning is being used in context. An idiom is not to be confused with other figures of speech such as a metaphor, which invokes an image by use of implicit comparisons (e.g., "the man of steel" ); a simile, which invokes an image by use of explicit comparisons (e.g., "faster than a speeding bullet"); and hyperbole, which exaggerates an image beyond truthfulness (e.g., like "missed by a mile" ). Idioms are also not to be confused with proverbs, which are simple sayings that express a truth based on common sense or practical experience.
An idiom is a phrase where the words together have a meaning that is different from the dictionary definitions of the individual words. In another definition, an idiom is a speech form or an expression of a given language that is peculiar to itself grammatically or cannot be understood from the individual meanings of its elements. In idioms, usually English learners would have a hard time understanding the real meaning if they did not have an English idioms dictionary. English has thousands of idioms. Most of English idioms are informal.