blank adj.

early 13c., "white, pale, colorless," from Old French blanc "white, shining," from Frankish *blank "white, gleaming," or some other Germanic source (compare Old Norse blakkr, Old English blanca "white horse;" Old High German blanc, blanch; German blank "shining, bright"). This is reconstructed to be from Proto-Germanic *blangkaz "to shine, dazzle," an extended form of PIE root *bhel- (1) "to shine, flash, burn," also "shining white."

The meaning "having empty spaces" is attested from c. 1400. The sense of "void of expression" (a blank look) is from 1550s. Spanish blanco, Italian bianco are said to be from Germanic. Related: Blankly, blankness.

late 14c. as the name of a small French coin; 1550s as "white space in the center of a target," from the same source as blank (adj.). The meaning "empty space" (in a document, etc.) is from c. 1570. The archaic meaning "losing lottery ticket" (1560s) is behind the figurative expression draw a blank "come up with nothing" (attested by 1822).

The court has itself a bad lottery's face,

Where ten draw a blank before one draws a place;

For a ticket in law who would give you thanks!

For that wheel contains scarce any but blanks.

[from Fielding's "The Lottery," 1732]

The word has been "for decorum's sake, substituted for a word of execration" [OED] at least since 1854 (for compound words, blankety-blank), from the use of blank lines in printing to indicate where such words or the letters forming the bulk of them have been omitted. From 1896 as short for blank cartridge (itself from 1826).

1540s, "nonplus, disconcert, shut up;" 1560s, "frustrate," from blank (adj.) in some sense. The sports sense of "defeat (another team) without allowing a score" is from 1870 (blank (n.) as "a score of zero in a game or contest" is from 1867). The meaning "become blank or empty" is by 1955. Colloquial sense of "forget (something) completely, go mentally blank" is by 1990s. Related: Blanked; blanking.