c. 1400, transitive, "to make white, cause to turn pale," from Old French blanchir "to whiten, wash," from blanc "white" (11c.; see blank (adj.)). In early use also "to whitewash" a building, "to remove the hull of (almonds, etc.) by soaking." Intransitive sense of "to turn white" is from 1768. Related: Blanched; blanching.
"to mark" (a tree, a trail), usually by cutting of a piece of bark so as to leave a white spot, 1750, American English, from blaze (n.) "white mark made on a tree" (1660s), for which see blaze (n.2).
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.
string of seashell beads used as money by Native Americans, 1630s, shortened from New England Algonquian wampumpeag (1620s), "string of white (shell beads);" said to be compounded from wab "white" + ompe "string" + plural suffix -ag.