プログレッシブ和英中辞典(第4版)の解説
いいそこなう【言い損なう】
❶〔言い違える〕make a mistake (in speaking);〔失言する〕make a slip of the tongue
彼はよく人の名を言い損なう
He often makes mistakes with people's names when he is talking.
どうもそれを言い損なったらしい
It seems I misstated it./I seem to have said it wrong.
❷〔言いそびれる〕fail to tell [mention];〔言い忘れる〕forget to tell
明日は休講だということを彼女に言い損なった
I forgot to tell her our class tomorrow is canceled.