Etymology

Latin Gnatho, name of a parasite in the Eunuchus of Terence, Ancient Greek γνάθων ‎(gnáthōn) (probably from the genitive plural form of γνάθος ‎(gnáthos, “jaw”)- the genitive singular, γνάθου ‎(gnáthou, “jaw”), was used adjectivally with the the meaning "greedy"); hence, a parasite in general.