1 a : used in or characteristic of familiar and informal conversation; also : unacceptably informal
b : using conversational style
2 : of or relating to conversation : conversational
Did You Know?
The noun colloquy was first used in English to refer to a conversation or dialogue, and when the adjective colloquial was formed from colloquy it had a similar focus. Over time, however, colloquial developed a more specific meaning related to language that is most suited to informal conversation—and it ultimately garnered an additional, disparaging implication of a style that seems too informal for a situation. Colloquy and colloquial trace back to the Latin verb colloqui, meaning “to converse.” Colloqui in turn was formed by combining the prefix com- (“with”) and loqui (“to speak”). Other conversational descendants of loqui in English include circumlocution, eloquent, loquacious, soliloquy, and ventriloquism. – www.merriam-webster.com