[bù dé yǐ]
act against one's will; be forced to; have no alternative but to; have to
have to be content with the second best; have no alternative but to give up one's preference
不得已而求其次
feel constrained to act against one's will; do sth. against one's will; have no alternative but to do sth.
不得已而为之
She had no alternative but to ask for a few days' leave.
实在不得已, 她只好请几天假。
Don't take this medicine unless it's absolutely necessary.
非万不得已不要用这种药。