ruinous

adjective

ru·​in·​ous ˈrü-ə-nəs 

1

: dilapidated, ruined

2

: causing or tending to cause ruin

ruinously adverb

ruinousness noun

Synonyms of ruinous

• disastrous
• fatal
• unfortunate
• catastrophic

Examples of ruinous in a Sentence

The house has fallen into a ruinous state.

a ruinous miscalculation of the financial markets left them bankrupt

Recent Examples on the Web

In this telling, Ivan appears as a precursor to Stalin and other ruinous Russian despots. — Foreign Affairs, 18 Aug. 2026

By that point, Didulo’s fictional laws had begun having ruinous effects. — Zander Sherman, Rolling Stone, 7 Aug. 2026

With his resignation, Starmer becomes the sixth British prime minister to resign since the seismic, and ultimately ruinous, Brexit referendum vote on June 2016. — Abid Rahman, HollywoodReporter, 22 June 2026

Distracting people from a ruinous war and domestic unrest with bread and circuses isn’t new. — Sun Sentinel Editorial Board, Sun Sentinel, 17 June 2026

Word History

First Known Use

14th century, in the meaning defined at sense 1

Kids Definition

ruinous

adjective

ru·​in·​ous ˈrü-ə-nəs 

: causing or tending to cause ruin : destructive

ruinously adverb