Loyal or faithful to, as in She knew he'd be true to his marriage vows, or, as Shakespeare had Polonius tell Hamlet, “This above all, to thine own self be true” (Hamlet, 1:3). [c. 1200]
Conforming to or consistent with, as in The speech was true to the party platform, or True to type, he died while working at his desk.
true to life. Consistent with reality, realistically represented, as in This painting is very true to life. [Early 1800s] For true to form, see under run to form.