faithful

If someone or something is faithful, they are loyal to a person or cause.

Example: My dog follows me everywhere I go. He is very faithful.

If someone is faithful, they have faith in something.

Example: People who go to church are faithful to their God.

If someone is faithful, they are able to be relied on; they are able to be trusted.

Example: My assistant does anything I ask him to. He is very faithful to me.

If something is faithful, it is close to something real.

Example: That painting is a very faithful copy of the Mona Lisa.

If someone is faithful, they have only had sex with their partner; they have not had sex with other people.

Example: They have been faithful to each other since they got married.