Fetching details from the dictionary...

dangerous; risky; hazardous; perilous; precarious
in danger; in jeopardy; critical; grave; at risk
uncertain; unreliable; insecure; unsteady; doubtful
close (call); narrow (escape)
look out!; watch out!; be careful!
ここは車が多くて危ないよ。
There are many cars here and it's dangerous.
台風の日の運転はとても危なかった。
Driving on the day of the typhoon was very dangerous.
この交差点は信号があり危なくない。
This intersection isn't dangerous since there's a traffic light.