Con-form, cydffurfio; unffurf; tebyg
Con-found, cymmysgu; dyrysu
Con-fuse, cymmysgu; annhrefnu
Con-fute, dadbrofi, gwrthbrofi
Con-geal, rhewi: tewychu
Con-gress, cyssenedd, eisteddfod; cynnadledd
Con-join, cydgyssylltu, cydio
Con-jure, tyngedu: swyno, conswrio
Con-nect, cyssylltu; cydlynu
Con-nive, goddef, cyd-ddwyn