What describes horizontal fibers used in weaving that can also be referred to as filling?

The term that describes horizontal fibers used in weaving, also known as filling, is weft. In the weaving process, the weft threads run across the loom horizontally, interlacing with the vertical threads known as warp. This interaction between weft and warp creates fabric. Understanding the specific roles of these terms is essential in the textiles and apparel industry, as they relate to the construction and quality of various fabrics.

The other options refer to different aspects of weaving or textiles. 'Warp' refers to the vertical threads that provide the fabric structure, while 'textile' is a general term that encompasses any material made through weaving, knitting, or felting. 'Fibers' denotes the raw materials used to create threads but does not specify the role of those threads in the weaving process. Therefore, the weft is the correct term for the horizontal fibers referred to in the question.