Ruinous means causing complete destruction or financial collapse. A ruinous decision, ruinous costs, ruinous to the family.
It is used most about money, where a ruinous expense is one nobody recovers from. Of a building it means fallen into ruin, which is the older and plainer sense.
1adjectiveruinousCausing complete destruction or financial collapse.
“The long legal battle proved ruinous, and the family lost their home.”
ruinous is a quality.
Latin ruinosus comes from ruina, a collapse, from ruere, to fall.
Latin
ruīnōsus
Old French
ruinos
Middle English
ruynous
English, today
ruinous
From Middle English ruynous, from Old French ruinos, ruineus, from Latin ruīnōsus. by surface analysis, ruin + -ous.
Etymology from Wiktionary, CC BY-SA