Ru"in*ous (?), a. [L. ruinosus: cf. F. ruineux. See Ruin.] 1. Causing, or tending to cause, ruin; destructive; baneful; pernicious; as, a ruinous project.

After a night of storm so ruinous.

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

3. Composed of, or consisting in, ruins.

Behold, Damascus . . . shall be a ruinous heap.
Isa. xvii. 1.

Syn. -- Dilapidated; decayed; demolished; pernicious; destructive; baneful; wasteful; mischievous.

-- Ru"in*ous*ly (#), adv. -- Ru"in*ous*ness, n.