expression, godan verb (-ku)
achieve enlightenment; attain spiritual awakening
Primarily a Buddhist term referring to reaching a state of profound spiritual insight or satori. Also used metaphorically for gaining deep understanding.
彼は長年の修行の末、ついに悟りを開いた。
After years of training, he finally achieved enlightenment.
この経験で彼
Through this experience, he seems to have gained deep insight into the truth of life.