悔恨 （カイコン） regret, remorse, repentance, contrition

悔悟 （カイゴ） remorse, repentance

痛悔 （ツウカイ） contrition, extreme regret, contrition (in Catholicism)

亢龍有悔 （コウリョウユウカイ） the arrogant dragon will have cause to repent, he who reaches the top is bound to fail if he is not prudent

悔いる （くいる） to regret

悔やむ （くやむ） to mourn, to lament, to be sorry, to regret, to repent

悔しい （くやしい） frustrated (over a failure, humiliation or injustice), annoyed, chagrined, (bitterly) disappointed, bitter, vexed, frustrating, annoying, regrettable