What does Staple mean?

A staple is a short length of fiber used to determine the quality of fibers based on their average length and fineness.

Heddels explains Staple

A staple is a short length of fiber used to determine the quality of fibers based on their average length and fineness. In general, longer staple lengths are more valuable in that they are more easily spun and create a smoother yarn than shorter staple lengths. The average staple length of cotton is between 26-27 mm, with more expensive cottons such as Egyptian and Pima having a staple length between 35-60 mm. Wool staples differ from other fiber staples in that they consist of a cluster of fibers rather than just one.

Additional Resources

Here is an example of staple fiber: