1580s, perhaps from Middle Dutch blinken "to glitter," of uncertain origin, possibly, with German blinken "to gleam, sparkle, twinkle," from a nasalized form of base found in Old English blican "to shine, glitter" (see bleach (v.)).
Middle English had blynke (c.1300) in the sense "a brief gleam or spark," perhaps a variant of blench "to move suddenly or sharply; to raise one's eyelids" (c.1200), perhaps from the rare Old English blencan "deceive." Related: Blinked; blinking. The last, as a euphemism for a stronger word, is attested by 1914.
1590s, "a glance;" see blink (v.). As is the case with the verb, there is a similar word in Middle English, in use from c.1300, that might represent a native form of the same root.
(Variations: bum or fritz or Fritz may replace blink) Not functioning properly; in poor condition: His pacemaker just went on the fritz
[entry form 1904+, fritz 1903+, bum 1896+; origin unknown; perhaps fr the notion that defective eyes or lights blink]