Pill: fabric flaw, not medicine

In everyday English, a pill is a small solid dose of medicine or supplement, swallowed whole. The word comes from Latin pilula, a little ball, and retains that sense of a compact sphere. But in textile production, the same word names a visible flaw in finished fabric: a small matted ball of fibers that forms on the surface through friction or wear.

A pill appears when short fibers or loose ends on a woven or knitted fabric surface are rubbed and tangled together by handling, washing, or use. Synthetic fibers, especially polyester and acrylic, are prone to pilling because they do not break or shed as readily as natural fibers. Once formed, these fiber balls sit on the surface like tiny knots, dulling the sheen and making expensive cloth look cheap and worn. A garment is said to be pilled when pills are visible across its surface.

The defect is distinct from fuzzing, in which fibers stand up loosely, or from bobbling, which refers to larger matted clusters. Pills are small, dense, and persistent; they do not brush or wash away easily. Quality control in textile mills includes pilling tests, in which fabric samples are rubbed or agitated in controlled ways to predict how likely a cloth is to pill in real use. High-end fabrics are engineered or finished to resist pilling through fiber selection, twist rates, and surface treatments.

The industrial meaning shares only the shape with the medical pill: both are small, round, and distinct objects. The textile sense likely arose from the visual resemblance, since fiber balls on cloth do resemble tiny pills. It is a metaphor of appearance rather than function, and one that has been technical enough to enter the vocabulary of mills and manufacturers as a formal term for a specific class of defect.