weft

Imagine a woven tapestry. The long threads running lengthwise are called the warp and act like the base. The threads that pass across them are the weft. They go over and under the warp threads to make the cloth. This is how woven fabric is made on a loom, how many baskets are formed, and why hair extensions are sometimes called "wefts" when the hair is attached in a strip. Without these crosswise threads, you would only have straight lines, not a finished woven material with shape, pattern, and strength.

The word "weft" comes from Old English roots meaning "that which is woven." It refers to the set of yarns woven across the warp in a fabric or piece of basketry. To picture it, think of the warp as the fixed set of threads and the weft as the threads that travel from side to side through them. In plain weaving, the weft passes over one warp thread and under the next, though other patterns are also possible. The way the warp and weft work together shapes the final cloth. Different materials, such as cotton, wool, silk, or plant fibers, can be used for the weft, and that choice affects the texture, color, weight, and strength of the finished textile.

Today, even though much textile production is automated, understanding the weft still matters in textile design, archaeology, and art restoration. The term can also appear in a wider sense for anything that feels interwoven, though its main use is still in weaving and textiles. So when you look at a woven piece, the weft is the crosswise part that helps turn a set of lengthwise threads into a complete material with pattern, texture, and form.