noun a bugbear; anything which terrifies.
2. bug ·noun one of certain kinds of crustacea; as, the sow bug; pill bug; bait bug; salve bug, ·etc.
3. bug ·noun one of various species of coleoptera; as, the ladybug; potato bug, ·etc.; loosely, any beetle.
4. bug ·noun an insect of the genus cimex, especially the bedbug (c. lectularius). ·see bedbug.
5. bug ·noun a general name applied to various insects belonging to the hemiptera; as, the squash bug; the chinch bug, ·etc.