FAITHLESS Copy link • FAITHLESSUnfaithful, perfidus: perfidiosus (one who deliberately violates the obligations of duty by breaking faith with anybody; perfidiosus, of him who does this habitually): infidelis (utterly without the virtue of fidelity; opposed to fidelis): infidus (without even natural trustworthiness; opposed to fidus). Unbelieving, qui non facile adduci potest, ut credat (general term): *qui veram Christi religionem non profitetur (in a Christian sense). To be faithless; Vid: “to break one’s FAITH.