puck·er 
(p
ŭk
ər)
v. puck·ered, puck·er·ing, puck·ers
v.tr. To gather into small wrinkles or folds: puckered my lips; puckered the curtains.
v.intr. To become gathered, contracted, and wrinkled.
n.1. A wrinkle or wrinkled part, as in tightly stitched cloth.
2. A facial expression in which the lips are tightly pulled together and pushed outward.
3. A tart flavor that causes one's lips to pucker: the pucker of lemon.
[ Probably frequentative of dialectal pock, bag, sack, variant of POKE3.]