The word brush has several meanings:

1. A tool with bristles attached to a handle, used for cleaning, grooming, or painting. You use a toothbrush to clean your teeth, a hairbrush to untangle your hair, and a paintbrush to apply color to a canvas. The bristles can be made from natural materials like animal hair or synthetic fibers like nylon.
2. To clean, groom, or apply something using a brush. You brush your teeth twice a day, brush your dog's coat to remove loose fur, or brush paint onto a fence.
3. To touch something lightly in passing. When you walk through tall grass, the stems brush against your legs. A bird might brush your shoulder as it flies past. This kind of contact is so brief and gentle that it barely registers.
4. A brief, often unpleasant encounter. If you have a brush with danger, you came close to something risky but escaped. A brush with the law means a minor run-in with the police or legal trouble.
5. Dense vegetation or wild undergrowth. In the American West, brush refers to shrubs and small trees growing wild. Firefighters worry about brush fires spreading quickly through this dry vegetation.