A blight is something that damages, ruins, or spoils things in a severe and widespread way. The word originally described plant diseases that kill crops: potato blight destroyed Ireland's potato harvest in the 1840s, causing terrible famine. When blight strikes a cornfield, the stalks turn brown and die. When it hits an apple orchard, the trees stop producing fruit.

The word now describes anything that ruins or degrades something once healthy or beautiful. An abandoned, crumbling building might be called a blight on the neighborhood, making the whole area look neglected. Graffiti covering playground equipment could be described as a blight. Urban planners talk about blighted areas where many buildings have fallen into disrepair.

You can also use blight as a verb: pollution blights a once-clear river, or corruption blights an otherwise honest organization. The word carries a sense of something spreading and persistent, not just a single problem but one that keeps causing damage over time. When something is blighted, it's been fundamentally harmed in a way that's hard to reverse.