Dictionary / Vocabulary / 言い損なう
いいそこなう
to say incorrectly; to use the wrong words; to make a slip of the tongue; to forget to say
Also written 言損なう、言いそこなう
ちょっとした言いそこないが思いがけない結果をもたらすことが多い。
A slip of tongue will often lead us to unexpected results.