やばい

やばい
adjective (i-adjective)
amazing; terrible; risky
1. amazing, awesome
Slang use expressing strong positive emotion about something impressive.
やばい、美味(おい)しい!
This is insanely good!
このラーメン、マジでやばい。
This ramen is seriously amazing.
昨日(きのう)のライブ、やばかった!最高(さいこう)だった!
Yesterday's concert was incredible! It was the best!
2. terrible, bad
Original meaning indicating a dangerous or problematic situation.
やばい、遅刻(ちこく)する!
Oh no, I'm going to be late!
財布(さいふ)(わす)れた。やばい。
I forgot my wallet. This is bad.
テストの点数(てんすう)がやばかったので、(おや)()せられない。
My test score was so bad I can't show it to my parents.
3. risky, dangerous
Describing something potentially harmful or illegal.
あの場所(ばしょ)はやばい。
That place is sketchy.
(よる)にあの(みち)一人(ひとり)(ある)くのはやばいよ。
It's dangerous to walk that road alone at night.
それはやばいことに()()しているんじゃないか。
Isn't that getting involved in something shady?

Originally meant 'dangerous/risky' but evolved among youth to mean 'amazing/cool'. Context determines meaning. Very informal. The positive sense became dominant in the 2000s. Common variations: やべえ (masculine), ヤバい (katakana for emphasis). One of the most versatile slang words.