Definition of "smudging"

Besides, the body paint would probably be visible on the sheets as dark smudgings, since the films were merely in black and white.

2004, Mark Thompson, Leather Folk: Radical Sex, People, Politics, and Practice, page 88

One of the most common forms of purification is done with smoke, using some kind of smoking or smudging.

2002, Raven Kaldera, Tannin Schwartzstein, The Urban Primitive: Paganism in the Concrete Jungle, page 36