The phrase "costs an arm and a leg" is an example of what?

The phrase "costs an arm and a leg" is recognized as an idiom because it conveys a meaning that is not derived from the literal interpretation of its individual words. Instead of suggesting that something literally costs body parts, it is understood to mean that a particular item or service is very expensive. Idioms are often culturally specific expressions that enrich language by conveying complex ideas or emotions in a succinct and metaphorical way.

While literal language would express ideas straightforwardly without embellishment, this phrase clearly does not fit that definition, as it employs figurative language. An allegory is a narrative that conveys a deeper moral or political meaning through symbolic figures and actions, whereas a proverb is a short, commonly known saying that typically offers advice or wisdom. Neither of these options captures the essence of the informal and metaphorical quality inherent in idioms, making the understanding and identification of idioms particularly important in language arts.