Which term refers to a conversational and informal style of language?

The term that refers to a conversational and informal style of language is colloquial. This term encompasses the use of everyday speech and language that is typical in casual conversation, often including informal expressions, slang, idiomatic phrases, and regional dialect. While formal language is characterized by precise and often complex vocabulary and structure, colloquial language embraces a more relaxed tone that is easily understood by the average person and conveys a sense of familiarity or intimacy.

Dialect, on the other hand, refers specifically to variations in language that are particular to a certain region or social group, which may include unique phrases but does not inherently denote informality. Prosaic typically describes straightforward, unembellished language that lacks poetic or imaginative quality, which contrasts with the vivacity and engagement often found in colloquial language. Thus, colloquial captures the essence of informal communication more accurately than the other options provided.