プログレッシブ和英中辞典(第4版)の解説
せいい【誠意】
sincerity; good faith
誠意のある［ない］
sincere [insincere]
彼の言うことには誠意が全くない
「You can't put any faith in [He's not at all serious about] what he says.／There is not a scrap of sincerity [good faith] in what he says.
誠意を示してほしい
I want you to show 「that you take your responsibilities seriously [that you are in earnest].
誠意を持って彼女のためにそう言った
He said so with her best interests at heart.