COLLOQUIAL (_comparative_ MORE COLLOQUIAL, _superlative_ MOST COLLOQUIAL)
* (linguistics) Denoting a manner of speaking or writing that is characteristic of familiar conversation; informal.
* Of or pertaining to a conversation; conversational or chatty.
Note that while _colloquy_ and _colloquium_ refer to _formal_ conversation, COLLOQUIAL refers instead specifically to _informal_ conversation.
* colloq., coll.