From Proto-Italic *tumēō, from Proto-Indo-European *tum-éh₁- (“to be swelling”), stative verb of *tum- (“to swell”). Cognates include Latin tūber, Sanskrit तुम्र (túmra, “big, strong”) and तूतुम (tūtumá, “strong, effective”), Lithuanian tumė́ti (“to become thick”), Ancient Greek τύμβος (túmbos, “swell”).