Definition of ruin.

ru·in (rn)
n.

1. Total destruction or disintegration, either physical, moral, social, or economic.
2. A cause of total destruction.
3.
a. The act of destroying totally.
b. A destroyed person, object, or building.
4. The remains of something destroyed, disintegrated, or decayed. Often used in the plural: studied the ruins of ancient Greece.
v. ru·ined, ru·in·ing, ru·ins
v.tr.
1. To destroy completely; demolish.
2. To harm irreparably.
3. To reduce to poverty or bankruptcy.
4. To deprive of chastity.
v.intr.
To fall into ruin.