a plant disease, typically one caused by fungi such as mildews, rusts, and smuts. Meaning of blight in English. Blight definition: You can refer to something as a blight when it causes great difficulties , and damages or. Blight definition is - a disease or injury of plants marked by the formation of lesions, withering, and death of parts (such as leaves and tubers). Blight is a rapid and complete chlorosis, browning, then death of plant tissues such as leaves, branches, twigs, or floral organs. any cause of impairment, destruction, ruin, or frustration: Extravagance was the blight of the family.