Someone or something that is faithful or reliable.
The practicing members of a religion or followers of a cause.
Consistent with reality.
Reliable; worthy of trust.
Loyal; adhering firmly to person or cause.
Injective in specific contexts, e.g. of representations in representation or functors in category theory.
Engaging in sexual relations only with one's spouse or long-term sexual partner.
Having faith.
Under one's control or influence.