What does "colloquial" mean?

Colloquial: Pertaining to, or used in, conversation, esp. common and familiar conversation; conversational; hence, unstudied; informal; as, colloquial intercourse; colloquial phrases; a colloquial style. -- Col*lo"qui*al*ly, adv. His [Johnson's] colloquial talents were, indeed, of the highest order. Macaulay.