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"
A ruinous process or course of action is one that is likely to lead to ruin. The economy of the state is experiencing the ruinous effects of the conflict. + ruinously ru·in·ous·ly cities ruinously choked by uncontrolled traffic
If you describe the cost of something as ruinous, you mean that it costs far more money than you can afford or than is reasonable. Many Britons will still fear the potentially ruinous costs of their legal system. + ruinously ru·in·ous·ly a ruinously expensive court case