faithless

The word 'faithless' is a transparent compound formed within English from the native suffix '-less' attached to the noun 'faith', which entered English via Old French from Latin fidēs. The Latin root fid- derives from the Proto-Indo-European (PIE) root bʰeydʰ-, meaning "to trust, confide, persuade." The literal, morphemic construction "faith" + "without" directly yields the modern meanings of being without loyalty (a breach of trust) or without religious belief. This evolution showcases how English combines a classical core concept of trust with a Germanic grammatical element to create a precise descriptor for a lack of fidelity.

Structure: faith (trust, belief) + less (without) - faith: From Old French feid, feit, from Latin fidēs (trust, faith, confidence). The core semantic element. - less: From Old English -lēas (devoid of, free from), an adjective-forming suffix indicating absence.