Source : Webster's Revised Unabridged Dictionary (1913)

Conversational \Con`ver*sa"tion*al\
   (k[o^]n`v[~e]r*s[=a]"sh[u^]n*al), a.
   Pertaining to conversation; in the manner of one conversing;
   as, a conversational style. --Thackeray.

Source : WordNet®

conversational
     adj : characteristic of informal spoken language or conversation;
           "wrote her letters in a colloquial style"; "the broken
           syntax and casual enunciation of conversational
           English" [syn: {colloquial}]