from The American Heritage® Dictionary of the English Language, 5th Edition.

• intransitive verb To close and open one or both of the eyes rapidly.
• intransitive verb To look in astonishment or disbelief, typically with the eyes blinking.
• intransitive verb To look through half-closed eyes, as in a bright glare; squint.
• intransitive verb To give off light with intermittent gleams; flash on and off.
• intransitive verb To pretend to be ignorant of; disregard or condone.
• intransitive verb To waver or back down, as in a contest of wills.
• intransitive verb To cause to blink.
• intransitive verb To hold back or remove from the eyes by blinking.
• intransitive verb To refuse to recognize or face.
• intransitive verb To transmit (a message) with a flashing light.
• noun The act or an instance of rapidly closing and opening the eyes or an eye.
• noun An instant.
• noun Scots A quick look or glimpse; a glance.
• noun A flash of light; a twinkle.
• idiom (in the blink of an eye) Very quickly.
• idiom (on the blink) Out of working order.
• idiom (without blinking an eye) Without showing any reaction.

from The Century Dictionary.

• To wink rapidly and repeatedly; nictitate.
• To see with the eyes half shut or with frequent winking, as a person with weak eyes; hence, to get a glimpse; peep.
• Figuratively, to look askance or indifferently.
• To intermit light; glimmer: as “a blinking lamp,”
• To gleam transiently but cheerfully; smile; look kindly.
• 6. To become a little stale or sour: said of milk or beer.
• To deceive; elude; shun.
• To see or catch sight of with half-shut eyes; dimly see; wink at.
• Figuratively, to shut one's eyes to; avoid or purposely evade; shirk: as, to blink a question.
• To balk at; pass by; shirk: as, a dog that never blinked a bird.
• To blindfold; hoodwink.
• noun A glance of the eye; a glimpse.
• noun A gleam; a glimmer; specifically, the gleam or glimmer reflected from ice in the polar regions: hence the term ice-blink (which see).
• noun A very short time; a twinkling: as, bide a blink.
• noun A trick; a scheme.
• noun plural Boughs thrown to turn aside deer from their course; also, feathers, etc., on a thread to scare birds.
• noun A fishermen's name for the mackerel when about a year old. See spike and tinker.

from the GNU version of the Collaborative International Dictionary of English.

• intransitive verb To wink; to twinkle with, or as with, the eye.
• intransitive verb To see with the eyes half shut, or indistinctly and with frequent winking, as a person with weak eyes.
• intransitive verb To shine, esp. with intermittent light; to twinkle; to flicker; to glimmer, as a lamp.
• intransitive verb To turn slightly sour, as beer, mild, etc.
• transitive verb To shut out of sight; to avoid, or purposely evade; to shirk.
• transitive verb Scot. To trick; to deceive.
• noun A glimpse or glance.
• noun Gleam; glimmer; sparkle.
• noun (Naut.) The dazzling whiteness about the horizon caused by the reflection of light from fields of ice at sea; ice blink.
• noun (Sporting), Prov. Eng. Boughs cast where deer are to pass, to turn or check them.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• verb To close and reopen both eyes quickly.
• verb To flash headlights on a car.
• verb To send a signal with a lighting device.
• verb To flash on and off at regular intervals.
• verb hyperbolic To perform the smallest action that could solicit a response.