憾
hàn
regret (sense of loss or dissatisfaction)
他没能去看那场演出，心里很遗憾。
tā méi néng qù kàn nà chǎng yǎnchū, xīn lǐ hěn yíhàn。
He was not able to go see that performance, and felt great regret in his heart.
这件事成了她一生中最大的遗憾。
zhè jiàn shì chéngle tā yīshēng zhōng zuì dà de yíhàn。
This matter became the greatest regret of her life.