The present participle of blight; causing or destroying with blight, or ruining someone's prospects or happiness.
From the verb 'blight' (to damage or ruin) plus '-ing' suffix creating the continuous form, with roots in Middle English 'blight' meaning disease.
The word 'blight' originally meant potato blight specifically—a disease so devastating to Ireland it caused famine—now it metaphorically means any kind of ruin.
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