comitas inter gentes (L.), international comity.
comme il faut (Fr.), as it should be: correct: approved by the fashionable world, genteel.
commune bonum (L.), common good.
communibus annis (L.), on the annual average.
communi consensu (L.), by common consent.
compagnon de voyage (Fr.), travelling companion.
compos mentis (L.), of sound mind, sane.
compte rendu (Fr.), an account rendered: report.
comptoir (Fr.), counter: counting-room.
con amore (It.), with love: very earnestly.