Difficult to express in words; hard to say — used when something is hard to state or describe.
彼の言葉は本当かどうか、言いがたいところがある。
It's hard to say whether his words are true.
その光景は言いがたい美しさがあった。
That scene had an indescribable beauty.
事情が複雑で、今は本当のことを言いがたい。
The situation is complicated, so I can't really say the truth right now.
Embarrassing or delicate to say; something you feel hesitant to tell someone because it's awkward or sensitive.
正直に言うと、彼に言いがたいことがある。
To be honest, there's something I find hard to tell him.
それを直接言うのは言いにくいが、改善が必要だ。
It's awkward to say that directly, but improvement is needed.