razor (n.) Look up razor at Dictionary.com
late 13c., from Old French raseor "a razor" (12c.), from raser "to scrape, shave," from Medieval Latin rasare, frequentative of Latin radere (past participle rasus) "to scrape, shave," possibly from an extended form of PIE root *red- "to scrape, scratch, gnaw." 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.