Loyal (adjective)

1. Giving or showing firm and constant support or allegiance to a person or institution.
2. Faithful to one's promises or commitments.
3. Giving or showing support or allegiance despite any setbacks or disadvantages.

Origin:

Middle english: from old french leial, from latin legalis "pertaining to the law", from lex, leg- "law".

Examples:

1. He was a loyal friend.
2. The company has a loyal customer base.
3. She is a loyal employee.
4. He is loyal to his country.
5. She is loyal to her beliefs.