suffix, i-adjective
very difficult to ...; nearly impossible to ...
Attaches to the -masu stem of a verb to express that the action is extremely difficult or almost impossible to do, often due to emotional, psychological, or inherent obstacles. Stronger than ～にくい.
彼の言っていることは信じがたい。
What he is saying is hard to believe.
This dish has a taste that is nearly impossible to eat.
あの映画のラストシーンは忘れがたい。
The final scene of that movie is unforgettable.