What is the meaning of ruinous?

adjective

• Extremely harmful; bringing physical or financial ruin.
  • usage: "a catastrophic depression"; "catastrophic illness"; "a ruinous course of action"
  • synonyms: catastrophic
• Causing injury or blight; especially affecting with sudden violence or plague or ruin.
  • usage: "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"
  • synonyms: blasting