Of a faithful heart; honest; sincere; not faithless or deceitful(adjective)
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Use "true-hearted" in a sentence
"In short, a lot of true-hearted Tea Partiers are going to learn an old lesson: their revolution was a lie."
"Finally, I found the story consistent and true-hearted to the Warhammer Fantasy setting, which I appreciate, because I want to be drowned into it, so to speak."
"They were bolder, sincerer, more true-hearted, more upright, and more united than those whom they overthrew."