blend: [13] Old English had a verb blendan, but it meant ‘make blind’ or ‘dazzle’. Modern English blend appears to come from blend-, the present stem of Old Norse blanda ‘mix’ (a relative of Old English blandan ‘mix’). The ultimate source of this is not clear, but it does not seem to be restricted to Germanic (Lithuanian has the adjective blandus ‘thick’ in relation to soup), so it may not be too far-fetched to suggest a link with blind, whose Indo-European ancestor *bhlendhos meant among other things ‘confused’.
blend (v.)
c. 1300, blenden, "to mix, mingle, stir up a liquid," in northern writers, from or akin to rare Old English blandan "to mix," blondan (Mercian) or Old Norse blanda "to mix," or a combination of the two; from Proto-Germanic *blandan "to mix," which comes via a notion of "to make cloudy" from an extended Germanic form of the PIE root *bhel- (1) "to shine, flash, burn" (see bleach (v.); also blind (adj.)). Compare Old Saxon and Old High German blantan, Gothic blandan, Middle High German blenden "to mix;" German Blendling "bastard, mongrel," and outside Germanic, Lithuanian blandus "troubled, turbid, thick;" Old Church Slavonic blesti "to go astray." Figurative use from early 14c. Related: Blended; blending.
blend (n.)
"mixture formed by blending," 1690s, from blend (v.).