A runner, or quick-draw. (from sense #2)
Any of various substances designed to extend any of several properties of a material.
Any substance added to food to bulk it out, with a higher protein content than a filler.
A phrase that extends an expression to include further members of a set, e.g. "and stuff", "or something".
Any of various components designed to extend the length of a device.
An athletic shoe, a trainer, a sneaker.