So unpleasant or painful as not to be endured or tolerated
Facing him again was an unbearable thought.
The air was hot and heavy and promised to become unbearable quickly.
On the flip side of the coin, she was finding life unbearable without him.
First, the jar of temperament between Comte and his wife had become so unbearable that they separated (1842).
On distillation of equal parts of dry potassium acetate and arsenious oxide, a colourless liquid of unbearable smell passes over, which is spontaneously inflammable and excessively poisonous.