From Latin 'colloqui' (to speak together) — language characteristic of informal conversation, not formal writing.
Used in or characteristic of ordinary, informal conversation rather than formal speech or writing. Conversational in style or register.
From Latin colloquium (conversation, conference), from colloquī (to speak together, to converse), from com- (together, with) + loquī (to speak). The Latin loquī traces to PIE *tolkʷ- (to speak, to say aloud), the root underlying eloquent, loquacious, soliloquy, and ventriloquist. The prefix com- intensifies the act: not just speaking
The word 'colloquial' is itself rarely used in colloquial speech — most people say 'informal' or 'casual' instead. This creates a delightful paradox: the word that names everyday language belongs to a formal, Latinate register that everyday speakers tend to avoid. You are statistically more likely to encounter 'colloquial' in a linguistics textbook or a dictionary