Nas"ty (?), a. [Compar. Nastier (); superl. Nastiest.] [For older nasky; cf. dial. Sw. naskug, nasket.]
Offensively filthy; very dirty, foul, or defiled; disgusting; nauseous.
Hence, loosely: Offensive; disagreeable; unpropitious; wet; drizzling; as, a nasty rain, day, sky.
Characterized by obcenity; indecent; indelicate; gross; filthy.
Syn. -- Nasty, Filthy, Foul, Dirty. Anything nasty is usually wet or damp as well as filthy or dirty, and disgusts by its stickness or odor; but filthy and foul imply that a thing is filled or covered with offensive matter, while dirty describes it as defiled or sullied with dirt of any kind; as, filthy clothing, foul vapors, etc.
© Webster 1913.