A betrayal of trust, commitment, or allegiance to someone or something important. Emotionally, it represents a breach in the fundamental bonds that create safety and security in relationships.
From Old French 'desloial' meaning 'not loyal,' combining 'des-' (opposite) with 'loyal' (from Latin 'legalis' meaning lawful). The emotional and psychological implications developed as understanding of trust and attachment deepened in the 20th century.
Try Another Word