What is the definition of an idiom?

An idiom is defined as a phrase whose meaning cannot be derived directly from the meanings of its individual words. For example, the idiom "kick the bucket" means to die, and it does not relate to the literal meanings of "kick" and "bucket." This quality makes idioms unique and often challenging for language learners, as understanding them requires familiarity with the cultural context and common usage rather than just the dictionary definitions of the words involved. The richness of idiomatic expressions adds depth to language, allowing for more colorful and vivid communication.