Old English toð (plural teð), from Proto-Germanic *tanth, *tunth (cf. Old Saxon, Danish, Swedish, Dutch tand, Old Norse tönn, Old Frisian toth, Old High German zand, German Zahn, Gothic tunþus), from PIE *dont-/*dent- "tooth" (cf. Sanskrit danta, Greek odontos, Latin dens, Lithuanian dantis, Old Irish det, Welsh dent). Plural form teeth is an instance of i-mutation. Application to tooth-like parts of other objects (saws, combs, etc.) first recorded 1520s.