True or faithful in allegiance; keeping faith or troth; constant in service, devotion, or regard; not false or treacherous: used especially of allegiance to the sovereign, government, or law, but applied to all other relations of trust or confidence: as, a loyal subject; a loyal friend; to be loyal to one's cause.Pertaining to or marked by allegiance or good faith; manifesting fidelity or devotion: as, loyal professions; loyal adherence to a principle.Synonyms See allegiance.