From Old Latin servos, from Proto-Italic *serwos (“guardian”), from Proto-Indo-European *ser-wo-s (“guardian”), possibly from *ser- (“watch over, protect”). Cognate with servō, Avestan 𐬵𐬀𐬭𐬀𐬌𐬙𐬌 (haraⁱti, “he heeds, protects”). By surface analysis, Proto-Indo-European *ser- + -vus.