| Ikat | "A traditional technique resulting in a streaky effect, created by tying and dyeing lengths of yarn before weaving." |
| Industrial textiles | "A category of technical textiles used as part of an industrial process, or incorporated into final products." |
| Intarsia | A motif design knitted in solid colours into a weft knitted fabric. |
| Interlaced yarn | see intermingled yarn. |
| Interlining | "An insulation, padding, or stiffening fabric, either sewn to the wrong side of the lining or the inner side of the outer shell fabric. The interlining is used primarily to provide warmth in coats, jackets, and outerwear." |
| Interfacing | "Fabrics used to support, reinforce and give shape to fashion fabrics in sewn products. Often placed between the lining and the outer fabric., it can be made from yarns or directly from fibers, and may be either woven, nonwoven, or knitted. Some interfaci |
| Intermingled yarn | "A multifilament yarn in which cohesion is imparted to the filament bundle by entwining the filaments instead of, or in addition to, twisting. The effect is usually achieved by passing the yarn under light tension through the turbulent zone of an air-jet. |
| Interlocking | "The stitch variation of the rib stitch, which resembles two separate 1 x 1 ribbed fabrics that are interknitted. Plain (double knit) interlock stitch fabrics are thicker, heavier, and more stable than single knit constructions." |
| Intumescent system (flame retardancy) | "A flame retardant system which undergoes charring and foaming upon thermal degradation (for example, when exposed to an ignition source such as a flame). A blown protective cellular char is formed on the surface of the textile, providing protection from |
| Islands-in-the-Sea | "A type of bicomponent yarn in which one component polymer is formed, during extrusion, as longitudinal strands within the matrix of a second polymer." |
| Isotactic | "A type of polymer structure in which groups of atoms that are not part of the backbone structure are located either all above or all below the atoms in the backbone chain, when the latter are arranged all in one plane." |