Smudge

noun

1. A blemish or smear, especially a dark or sooty one.

   "There was a smudge on the paper."

2. Dense smoke, such as that used for fumigation.
3. A heap of damp combustibles partially ignited and burning slowly, placed on the windward side of a house, tent, etc. to keep off mosquitoes or other insects.
4. (especially in the phrase "smudge stick" = "stick of incense") A quantity of herbs used in suffumigation.