A knot or other defect in a thread or yarn which hinders spinning or weaving; a twit.
twitter: a knot that stops the thread cold
In textile mills, a twitter is a hard knot or irregular lump in raw thread or yarn that obstructs passage through spindles, looms, or finishing equipment. When a twitter encounters a heddle eye, a reed opening, or a spindle, it catches and halts the thread, forcing operators to stop the machine, find the defect, and often cut out and rejoin the damaged section. Even small twitterings, scarcely visible to the eye, can stall production unexpectedly.
Twitters arise at several points in the fiber-to-fabric chain. Carded or combed fibers may clump if moisture, static, or improper mixing occurs before spinning. Raw cotton, wool, or synthetic staple can carry vegetation, seed fragments, or processing debris that knots during twist. In ring spinning, tension surges or spindle wobble sometimes fold yarn back on itself and lock it solid. A twitter in loosely twisted yarn is easier to spot and remove than one buried in a tightly wound cop or bobbin.
The term's origin reflects mill vocabulary: to twitter means to twist or tangle, from the jerking motion a thread makes when it suddenly catches. Operators would twitter out a defective length or twitter the yarn to loosen a knot. The name endured in British and European spinning houses well into the twentieth century, though electronic and mechanical quality-control systems have reduced manual detection.
Twittering has real cost: every halt cuts spindle hours, every rejoin introduces a weak point that may break downstream, and every search for the fault wastes labor. Mills invested in better carding density, moisture control, and lint removal to reduce twittering. High-speed frames could not tolerate them at all, so roving and thread destined for fast machinery was inspected more carefully or passed through fineness-grading equipment before spinning.
In modern usage, twitter is nearly obsolete, replaced by neps (fiber clusters), slubs (thick places), and contamination as diagnostic terms. However, the word persists in old mill manuals and among longtime spinners and weavers, where it describes that specific nuisance: a localized hard point that does not spin smooth and will not slide through the loom.