blotch

Imagine a perfectly clean white wall… now picture someone throwing a handful of wet mud at it. That messy, uneven mark is a blotch—an irregular spot or stain that stands out from the surrounding surface. It is usually larger and less defined than a clean drop or small spot.

A detective might notice a suspicious blotch on a suspect's sleeve, and a gardener might worry about a blotch of mildew on a rose petal. Sometimes blotches are part of nature—like irregular patterns on certain breeds of cattle—but they still register as visual disruptions on a generally uniform surface.

A blotch is a visible, irregularly shaped area of color or residue that disrupts the appearance of a surface. It can be a patch of dirt, liquid, pigment, mildew, or skin change, and it is often perceived as untidy or unsightly. Unlike a neat circle or precise line, a blotch is typically broad, uneven, and blurred around the edges.

You might encounter a blotch of oil on a garage floor, an uneven blot of paint in a rushed mural, or a blotchy complexion caused by an allergy. In biology, art, and natural history, it is often a neutral term for the irregular markings on animals, leaves, fruit, or other objects. In everyday speech, the adjective "blotchy" is the more common form when describing skin.

The phrase "a blot on one's reputation" is a separate idiom and not the same as this word. A blotch generally refers to a literal patch, stain, or color mark, especially one that is noticeable and out of place.