loyal

a. 忠诚的,忠心的
ad. 忠诚地,忠实地
n. 忠贞,忠诚,忠实

The soldiers are loyal to their country.

士兵们忠于他们的国家。

I may say in all sincerity that you have been my most loyal friend.

我可以非常真诚地说，你一直是我最忠实的朋友。