Entries related to blindly
Old English blind "destitute of sight," also "dark, enveloped in darkness, obscure; unintelligent, lacking mental perception," probably from Proto-Germanic *blindaz "blind" (source also of Old Frisian, Old Saxon, Dutch and German blind, Old Norse blindr, Gothic blinds "blind"), perhaps, via notion of "to make cloudy, deceive," from an extended Germanic form of the PIE root *bhel- (1) "to shine, flash, burn."
The original sense would be not "sightless" but rather "confused," which perhaps underlies such phrases as blind alley (1580s; Chaucer's lanes blynde), which is older than the sense of "closed at one end" (1610s).
Meaning "not directed or controlled by reason" was in Old English. Meaning "without opening for admitting light or seeing through" is from c. 1600. In reference to acting without seeing or investigating first, by 1840; of aviators flying without instruments or without clear observation, from 1919.
The twilight, or rather the hour between the time when one can no longer see to read and the lighting of the candles, is commonly called blindman's holiday. [Grose, 1796]
common adverbial suffix, forming from adjectives adverbs signifying "in a manner denoted by" the adjective, Middle English, from Old English -lice, from Proto-Germanic *-liko- (cognates: Old Frisian -like, Old Saxon -liko, Dutch -lijk, Old High German -licho, German -lich, Old Norse -liga, Gothic -leiko); see -ly (1). Cognate with lich, and identical with like (adj.).
Weekley notes as "curious" that Germanic uses a word essentially meaning "body" for the adverbial formation, while Romanic uses one meaning "mind" (as in French constamment from Latin constanti mente). The modern English form emerged in late Middle English, probably from influence of Old Norse -liga.
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he felt around his desk blindly
he picked a wife blindly
they bought the car blindly