as in conk out, 1918, coined by World War I airmen, perhaps in imitation of the sound of a stalling motor, reinforced by conk (v.) "hit on the head," originally "punch in the nose" (1821), from conk (n.), slang for "nose" (1812), perhaps from fancied resemblance to a conch (pronounced "conk") shell.
: I couldn't get over marveling at how their hair was straight and shiny like white men's hair; Ella told me this was called ''conk''
To apply a mixture sometimes containing lye to the head in order to straighten kinky hair
[1940s+ Black; probably fr Congolene, trademark of a preparation used to straighten hair, influenced by conk1]
To die; cease to operate; conk out: A year after that, a spinster aunt conked (WWI Royal Flying Corps)