Source : Webster's Revised Unabridged Dictionary (1913)

Unchaste \Un*chaste"\, a.
   Not chaste; not continent; lewd. -- {Un*chaste"ly}, adv. --
   {Un*chaste"ness}, n.

Source : WordNet®

unchaste
     adj : not chaste; "unchaste conduct" [ant: {chaste}]