razor (n.)

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.

also razor-back, type of hog with a sharp ridge-like back, 1849, from razor (n.) + back (n.). Especially of feral hogs in the U.S. South. Also used of narrow ridges of land.

*rēd-, Proto-Indo-European root meaning "to scrape, scratch, gnaw."

It forms (possibly) all or part of: abrade; abrasion; corrode; corrosion; erase; erode; erosion; radula; rascal; rase; rash (n.) "eruption of small red spots on skin;" raster; rat; raze; razor; rodent; rostrum; tabula rasa.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit radati "scrapes, gnaws," radanah "tooth;" Latin rodere "to gnaw, eat away," radere "to scrape;" Welsh rhathu "scrape, polish."