Characteristic of informal spoken language or conversation:
— Wrote her letters in a colloquial style.

synonym: conversational.

Roget 521: metaphorical, figurative, catachrestical^†, typical, tralatitious^†, parabolic, allegorical, allusive, anagogical^†; ironical; colloquial; tropical.   

Roget 563: neologic^†, neological^†; archaic; obsolete etc. (old) 124; colloquial; Anglice^†.   

Roget 588: conversing etc. v.; interlocutory; conversational, conversable^†; discursive, discoursive^†; chatty etc. (sociable) 892; colloquial.   

Polish: konwersacyjny