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