What are idioms?

Idioms are phrases or expressions in which the meanings of the individual words are not directly related to the overall meaning of the phrase. This means that when one encounters an idiom, understanding its intended meaning requires familiarity with the cultural or contextual background in which it is used. For instance, saying "it's raining cats and dogs" does not mean that pets are falling from the sky; instead, it figuratively describes heavy rain.

This characteristic of idioms is what sets them apart from literal phrases. While the other options describe different aspects of language, such as common beliefs or emotional expressions, they do not capture the unique quality of idioms wherein the figurative meaning diverges from the literal interpretation of the words involved.