崩壊【ほうかい】
collapse, crumbling, breaking down, caving in, (radioactive) decay, disintegration
破壊【はかい】
destruction, disruption, (application) crash
壊滅【かいめつ】
destruction, annihilation, devastation, catastrophe
壊す【こわす】
to break, to destroy, to demolish, to wreck, to ruin, to spoil, to damage, to break (a bill, etc.)
壊れる【こわれる】
to be broken, to break, to fall apart, to collapse, to be destroyed, to be damaged, to break (down), to stop working, to fall through (of a plan, deal, etc.), to collapse, to break down (of a relationship, negotiations, etc.), to be broken off, to be ruined (of an atmosphere, one's image, etc.)