I-adjective (keiyoushi)
tough; hard; severe; demanding; harsh
フーッ、この坂道はきついよ。でも帰りは楽だよね。Whew! This is a tough hill. But coming back sure will be a breeze. determined; strong-minded; forceful; formidable; fierce
strong (e.g. sunlight, alcohol); severe; intense
(too) tight; constricting; close
extreme; unusually strong
Also written キツイ、キツい