colloquialism; vernacular expression
Refers to a word or expression used in everyday conversation rather than formal writing.
"Meccha" is often used as a colloquialism in the Kansai region.
It's better to avoid this colloquialism in formal writing.
俗語 is slang, often more informal or subculture-specific than 会話語, which is simply conversational.
Compound of 会話 (conversation) and 語 (word, language). The term is transparently derived from its components.