disputer

Etymology tree
Proto-Indo-European *dwóh₁
Proto-Indo-European *d(w)is-
Proto-Italic *dis-
Latin dis-
Latin putus
Proto-Indo-European *-h₂
Proto-Indo-European *-éh₂
Proto-Indo-European *-yéti
Proto-Indo-European *-eh₂yéti
Proto-Italic *-āō
Latin -ō
Latin putō
Latin disputo
Old French desputerbor.
Middle English disputen
English dispute
Proto-Indo-European *-yósder.
Proto-Italic *-āzijos
Latin -āriusnom.
Latin -āriusbor.
Proto-Germanic *-ārijaz
Proto-West Germanic *-ārī
Old English -ere
Middle English -ere
English -er
English disputer
From dispute + -er.