Bagsik (adj) means strong, strength, power. Could refer to a person or things.
Sample:
Bagsika pud ana niya oi. (He is so nasty, cruel)
AngBaygon-katol, mabagsik sa lamok (Baygon katol is very effective against mosquito)
If used to describe a person, signifies negative behavior. Similar bisaya term, isog, barumbado, hambugero. Nothing afraid of.