Home › Words › U › uterotoninuterotoninuterotonin · noun — A uterotonic substance present in the amniotic fluid during labour.Definition from Wiktionary (CC BY-SA 3.0).EtymologyFrom uterotonic + -in.nounA uterotonic substance present in the amniotic fluid during labourDefinitions & examples from Wiktionary (CC BY-SA 3.0).