peligroso
dangerous
peril
danger
+
-oso
full of
Peligroso means dangerous and can be thought of as peril0 (danger0) + -oso1 (full of1), so it's something 'full of peril' or dangerous.
adjective
- dangerousInvolving or causing danger or riskConducir ebrio es muy peligroso. // Driving drunk is very dangerous.