This is the 14118th most frequent Russian word.
опасен
Dangerous.
The word 'опасен' describes the bridge as being dangerous in nature, indicating its general unsafety.
Этот мост опасен для перехода.
This bridge is dangerous to cross.
Here, 'опасной' is used to modify 'ситуация', describing the situation as having reached a level of danger.
Ситуация стала слишком опасной, чтобы продолжать.
The situation has become too dangerous to continue.
In this case, 'опасен' describes a person as currently being dangerous, implying a current state or threat.