late 13c., from Old French raseor "a razor" (12c.), from raser "to scrape, shave" (see rase). Razor clam (1835, American English) so called because its shell resembles an old folding straight-razor. Razor-edge figurative of sharpness or a fine surface from 1680s.
The Nazarites were forbidden to make use of the razor (Num. 6:5; Judg. 13:5). At their consecration the Levites were shaved all over with a razor (Num. 8:7; comp. Ps. 52:2; Ezek. 5:1).