constrainer

Etymology tree
Proto-Indo-European *ḱe?
Proto-Indo-European *ḱóm
Proto-Italic *kom
Proto-Italic *kom-
Latin cōn-
Proto-Indo-European *strengʰ-der.
Proto-Indo-European *streyg-der.
Latin stringō
Latin cōnstringōder.
Old French constreindrebor.
Middle English constreinen
English constrain
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 constrainer
From constrain + -er.