ruinous

From Middle English ruynous, from Old French ruinos, ruineus, from Latin ruīnōsus. By surface analysis, ruin +‎ -ous.

• IPA^(key): /ˈɹuː.ɪnəs/

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ruinous (comparative more ruinous, superlative most ruinous)

1. Causing ruin; destructive, calamitous.
2. Extremely costly; so expensive as to cause financial ruin.

   They were forced to completely replace the roof at ruinous expense.

   • 2025 September 23, Donald Trump, speech at United Nations:

     We are rapidly reversing the economic calamity we inherited from the previous administration, including ruinous price increases and record-setting inflation, inflation like we've never had before.

3. Characterized by ruin; ruined; dilapidated; as, an edifice, bridge, or wall in a ruinous state.

• (characterized by ruin): See Thesaurus:ramshackle

• ruinously
• ruinousness

• “ruinous”, in Webster’s Revised Unabridged Dictionary, Springfield, Mass.: G. & C. Merriam, 1913, →OCLC.
• William Dwight Whitney, Benjamin E[li] Smith, editors (1911), “ruinous”, in The Century Dictionary […], New York, N.Y.: The Century Co., →OCLC.
• “ruinous”, in OneLook Dictionary Search.

• urinous