Other forms: ruins, ruined, ruining
A ruin is the broken remains of an old building. Roman ruins, fall into ruin, the ruins of the abbey.
The plural is the usual form for a site: the ruins of the castle. A building falls into ruin when nobody maintains it, and the ruin as an object of admiration is a fairly modern taste — the eighteenth century built fake ones on purpose. As a verb, to ruin is to destroy or spoil, from a whole harvest to an evening. Note ruined; and financial ruin.
1nounsiteThe broken remains of an old building.
“We explored the ruins of an old castle on the hill.”
2verbdestroyTo destroy or spoil something.
“The rain ruined our picnic, so we ate our sandwiches in the car.”
Too few real examples of this word to estimate which sense is commonest.
Latin ruina comes from ruere, to fall down or rush. The word is about collapse itself rather than about what is left standing.
Latin
ruīna — overthrow, ruin
Old French
ruine
Middle English
ruyne
English, today
ruin
Built from
From Middle English ruyne, ruine, from Old French ruine, from Latin ruīna (“overthrow, ruin”), from ruō (“to fall down, tumble, sink in ruin, rush”).
Etymology from Wiktionary, CC BY-SA