1. Godan verb with 'ku' ending, Intransitive verb

   to notice; to realize; to realise; to become aware (of); to perceive; to sense; to suspect

   彼は危険に気づいていなかった。

2. to regain consciousness; to come to (one's senses); to come round

   see 気がつく

Also written 気付く【きづく】kizuku