Etymology tree
Proto-Indo-European *h₃enh₂-
Proto-Indo-European *-os
Proto-Indo-European *h₃énh₂os
Proto-Italic *onos
Latin onus
From Proto-Italic *onos, from Proto-Indo-European *h₃énh₂os, from the root *h₃enh₂-. Cognate with Sanskrit अनस् (ánas, “heavy cart; mother; birth; offspring”). See Ancient Greek ὄνομαι (ónomai, “impugn, quarrel with”).