1540s, "completely destroy," an alteration of racen "pull or knock down" (a building or town), from earlier rasen (14c.), etymologically "to scratch, slash, scrape, erase," from Old French raser "to scrape, shave," from Medieval Latin rasare, frequentative of Latin radere (past participle rasus) "to scrape, shave." This has cognates in Welsh rhathu, Breton rahein "to scrape, shave." Watkins says it is "possibly" from an extended form of the PIE root *red- "to scrape, scratch, gnaw." But de Vaan writes, "Since this word family is only found in Italo-Celtic, a PIE origin is uncertain." From 1560s as "shave off, remove by scraping," also "cut or wound slightly, graze." Related: Razed; razing.
late 14c., "remove by scraping, rub, erase," especially "to remove writing by scruaping it out," from Old French raser "to scrape, shave," from Medieval Latin rasare, frequentative of Latin radere (past participle rasus) "to scrape, shave" (see raze (v.)). Meaning "level to the ground or the supporting surface" is from 1530s (compare raze). Related: Rased; rasing.
c. 1300, rasour, "sharp-edged instrument for shaving or cutting hair," from Old French rasor, raseor "a razor" (12c.), from raser "to scrape, shave," from Medieval Latin rasare, frequentative of Latin radere (past participle rasus) "to scrape, shave" (see raze (v.)). Compare Medieval Latin rasorium.
As a verb, by 1827 as "shave with a razor," 1937 as "assault with a razor." The razor clam (1835, American English) is so called because its shell resembles an old folding straight-razor. Razor edge, figurative of sharpness or a fine surface, is by 1680s. Razor-blade is attested by 1816.
