faithful

/ˈfeɪθfəl/ adjective

Definition

RELATIONSHIP › If your husband, wife, or partner is faithful, they do not have a sexual relationship with anyone else: a faithful husband They remained faithful to each other throughout their long marriage.

LOYAL › always loyal: his trusted and faithful servant

NOT CHANGED › not changing any of the original details, facts, style, etc: Does the film adaptation stay faithful to the novel? → Opposite unfaithful

faithfulness noun [U]

(Definition of faithful adjective from the Cambridge Learner's Dictionary © Cambridge University Press)