Devoid of any hypocrisy or pretense
He seemed sincere, but it could have been an act.
It was something she had always liked about him, mostly because he was sincere about it.
Of a quick and cultivated intelligence, he had a sincere love of letters and art.
His letters show that he had a very sincere love for, and an enlightened appreciation of, good literature.
"I feel like I should apologize for … whatever it is you're feeling," he said with what he hoped sounded like a sincere attempt to empathize.