Learner's definition of FAITHFUL
[more faithful; most faithful]
1 : having or showing true and constant support or loyalty — often + to
Despite his problems, his friends have remained faithful to him.
She has always remained faithful to the values she learned as a child.
2 : deserving trust : keeping your promises or doing what you are supposed to do — often + to 3 : not having sex with someone who is not your wife, husband, girlfriend, or boyfriend 4 : exact and accurate — often + to
1 : the people who believe or participate in a religion 2 : the people who are loyal members or supporters of a group or organization