- falling or fallen into ruin; dilapidated; decayed
- bringing or tending to bring ruin; very destructive or harmful; disastrous: ruinous floods
Origin of ruinousMiddle English ruinouse ; from Classical Latin ruinosus
- Causing or apt to cause ruin; destructive: a ruinous habit; a ruinous rivalry.
- Falling to ruin; dilapidated or decayed.
(comparative more ruinous, superlative most ruinous)