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intolerable; unbearable; unendurable
irresistible; tremendous; out of this world
cannot help (doing); cannot but do; anxious to do; cannot get enough of
今日のこの暑さは本当に堪らないね。
This heat is unbearable, isn't it?
痛みが堪らなくて病院に行った。
The pain was unbearable so I went to the hospital.
寂しくて堪らない気持ちです。
I feel unbearably lonely.