ruin (n.) Look up ruin at Dictionary.com
late 14c., "act of giving way and falling down," from Old French ruine "a collapse" (14c.), and directly from Latin ruina "a collapse, a rushing down, a tumbling down" (source also of Spanish ruina, Italian rovina), related to ruere "to rush, fall violently, collapse," from PIE *reue- (2) "to smash, knock down, tear out, dig up" (see rough (adj.)). Meaning "complete destruction of anything" is from 1670s. Ruins "remains of a decayed building or town" is from mid-15c.; the same sense was in the Latin plural noun.
ruin (v.) Look up ruin at Dictionary.com
1580s (transitive), from ruin (n.). Intransitive sense "fall into ruin" is from c.1600. Financial sense is attested from 1660. Related: Ruined; ruining.