ru·in 
(rĭn)
(rĭn)n.
1. often ruins
a. The state of being physically destroyed, collapsed, or decayed: The castle fell into ruin.
b. The state of being extensively harmed or damaged: Our vacation plans are in ruins.
c. Poverty of bankruptcy: Their decision brought the bank to ruin.
2.
a. often ruins A destroyed, collapsed, or decayed building or other physical entity: the ruins of the old mill.
b. One that has been extensively damaged or harmed: He is a ruin of his former self.
3. A cause of destruction or irreparable harm or loss: Gambling will be his ruin.
tr.v. ru·ined, ru·in·ing, ru·ins
1. To cause (a building, for example) to be in a destroyed, collapsed, or decayed state.
2.
a. To harm or damage the quality or value of (something) irreparably: A bad diet ruined his health.
b. To harm or damage the enjoyment or experience of (something) greatly: ruined the movie by talking throughout it; ruined the book by giving away the ending.
3. To reduce to poverty or bankruptcy: Bad loans ruined the banker.
[Middle English ruine, from Old French, from Latin ruīna, from ruere, to rush, collapse.]
ruin·a·ble adj.
ruin·er n.