1. Causing, or tending to cause, ruin; destructive; baneful; pernicious; as, a ruinous project. After a night of storm so ruinous. Milton. 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. -- ...
