grunt (v.)

Old English grunnettan "to grunt," frequentative of grunian "to grunt," probably imitative (compare Danish grynte, Old High German grunnizon, German grunzen "to grunt," French grogner, Latin grunnire "to grunt"). Related: Grunted; grunting. Grunter "a pig" is from 1640s.

1550s, from grunt (v.); as a type of fish, from 1713, so called from the noise they make when hauled from the water; meaning "infantry soldier" emerged in U.S. military slang during Vietnam War (first recorded in print 1969); used since 1900 of various low-level workers. Grunt work first recorded 1977.