The horizontal platform of a stair. When the exposed tread is wood, it is composed of a solid or glued-together single piece, or made up of flooring pieces that are trimmed off at the front lip of the tread with a moulding called a stair nosing.
The horizontal part of a step on which the foot treads. Trim -- the finish materials in a building, such as moldings, applied around openings (window trim, door trim) or at the floor and ceiling of rooms ( base board, shoe molding, cornice, and other moldings.)
The actual surface portion of a trail upon which users travel excluding backslope, ditch, and shoulder. Common tread surfaces are native material, gravel, soil cement, asphalt, concrete, or shredded recycled tires.
The tread of a tire or caterpillar track refers to the pattern visible on its circumference that makes contact with the road. As tires are used, the tread is worn down limiting their effectiveness in providing traction. A worn tire tread can be replaced with a process known as retreading.