ˈpəs(ˌ)chül, -ˌst(y)ül noun
( -s )
Etymology: Middle English, from Latin pustula, pussula; akin to Greek physa bellows, bladder, bubble, Lithuanian puslė bladder — more at fog
1. : a small circumscribed elevation of the skin containing pus and having an inflamed base
2. : any small elevation or spot on a plant resembling a blister ; especially : a mark on a leaf due to the rupture of surface tissues overlying spore masses or fruiting structures of a parasitic fungus
3.
a. : a wart or dermal excrescence in some amphibians (as toads)
b. : a colored point or a swelling resembling a blister (as on the integument of an insect)