Derivational etymology. Although it is a derivative of γόμφος "peg", γομφίος "molar" receives a different etymology. This results from the fact that the referents are quite different, γόμφος referring to a wooden or metal artefact, while γομφίος refers to a tooth. Therefore, rather than assuming that "tooth" and "peg" were the proper meaning and the metaphoric meaning of one and the same word, as we modern would, Greek etymologists provided two completely different etymologies because their primary concern was meaning rather than form. So, the tooth is called γομφίος, allegedly from *γαμφίος (a ghost-word invented for the sake of the etymology) because it "curves" food (functional etymology: the molar crushes food, therefore "curves" it), or because it is inserted into the jaw, which is "curved" (metonymical etymology). See, however, an etymology deriving γόμφος from γομφίος (γόμφος / γομφίος)