Wink or blink; close and open the eyelids in a quick, often reflexive motion. Nictate has a clinical air, an action noted by a careful observer rather than casually described.

From Latin nictāre "to wink," a frequentative form related to nictāre/nīcere "to wink or move quickly." The crispness of the word imitates the act. Brief, tight, repeated.