iuvo.

Uncertain. The word probably originates from a PIE reduplicated present *h₁íHewHeti (“to help”), from the root *h₁ewH-. This same PIE verb may be the source of Hittite [Term?] (/⁠iyauwatta⁠⁠/, “to be healed, recover”). Proto-Indo-European *h₁íHewHeti may have produced an athematic Proto-Italic verb *iow-, which then became iuvere. The form iuvere is likely the source of iuvō, -āre, although the exact process of derivation is unclear. It may have developed as an iterative to iuvere or it may have emerged as a back-formation from adiuvō, -āre, which—according to this theory—would have derived from ad- + iuvere via the same pattern as pellō, pellere and appellō, appellāre. It is unusual for PIE *-ew- to yield Latin Latin *-u-. De Vaan suggests that iuvere may have replaced earlier *iovere by analogy with iuvāre, which itself—if the back-formation hypothesis is accepted—may have replaced earlier *iovāre by analogy with adiuvō.