grunt

(noun) the short low gruff noise of the kind made by hogs. Synonyms: oink.

(noun) an unskilled or low-ranking soldier or other worker. Examples: "Infantrymen in vietnam were called grunts." "He went from grunt to chairman in six years."

(noun) medium-sized tropical marine food fishes that utter grunting sounds when caught.

(verb) issue a grunting, low, animal-like noise. Example: "He grunted his reluctant approval."