Merriam-Webster's Collegiate® Dictionary, 11th Edition
FLICKER
I. verb (flickered; flickering)
Etymology: Middle English flikeren, from Old English flicorian Date: before 12th century intransitive verb to move irregularly or unsteadily ; flutter , to burn or shine fitfully or with a fluctuating light , to appear briefly, transitive verb to cause to flicker, to produce by flickering, flickeringly adverb
II. noun
Date: 1822
1. an act of flickering, a sudden brief movement, a momentary quickening , a slight indication ; hint ,
2. a wavering light, a repeated momentary defect in a cathode-ray tube image caused especially by slow scanning of the screen, movie , flickery adjective
III. noun
Etymology: probably imitative of its call
Date: 1809
a large barred and spotted North American woodpecker ( Colaptes auratus ) with a brown back that commonly forages on the ground for ants