What are idioms?

Idioms are phrases whose meanings cannot be understood solely by interpreting the individual words within them. For example, the expression "kick the bucket" does not literally involve kicking a bucket; instead, it means to die. Understanding idioms requires familiarity with the cultural and contextual usage of the phrases, as their meanings are often figurative and specific to particular languages or communities.

The other options fail to capture the essence of what idioms represent. While phrases with multiple meanings (as mentioned in another choice) exist, they are not the same as idioms, which have specific, culturally recognized interpretations. Common phrases used in everyday conversation may or may not be idiomatic; not all common phrases are idioms. Lastly, expressions that are universally understood across cultures would not be classified as idioms, since idioms are typically rooted in specific cultural contexts and may not hold the same meaning or recognition across different languages or societies.