Nasty \Nas"ty\, a. [Compar. Nastier; superl. Nastiest.]

[For older nasky; cf. dial. Sw. naskug, nasket.]

1. Offensively filthy; very dirty, foul, or defiled; disgusting; nauseous.

2. Hence, loosely: Offensive; disagreeable; unpropitious; wet; drizzling; as, a nasty rain, day, sky.

3. Characterized by obcenity; indecent; indelicate; gross; filthy.

Syn: Nasty, Filthy, Foul, Dirty.

Usage: 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.

Source: Webster's Revised Unabridged Dictionary (1913)