Definition of Ruinous

• extremely harmful; bringing physical or financial ruin; "a catastrophic depression"; "catastrophic illness"; "a ruinous course of action"
• causing injury or blight; especially affecting with sudden violence or plague or ruin; "the blasting effects of the intense cold on the budding fruit"; "the blasting force of the wind blowing sharp needles of sleet in our faces"; "a ruinous war"