Final answer:
The term for synthetic fibers that measure less than one denier per filament and are often made of polyester is microfiber, which is finer than silk and used in various products for its unique properties such as softness and absorption.
Step-by-step explanation:
The term that refers to synthetic fibers measuring less than one denier per filament and typically made of polyester is microfiber. These extremely fine fibers are even thinner than silk, which is about one denier and considered very delicate. The diameter of microfiber is less than ten micrometres, making it much finer than a human hair. The most common types of microfibers are made from polyesters and polyamides such as nylon, among others. They are utilized in various products, including apparel like mats, knits, and weaves; household items like upholstery and cleaning products; and industrial applications like filters. These fibers are chosen for their particular characteristics like softness, toughness, absorption, and filtering capabilities.
Nylon, on the other hand, is a type of polyamide known for its strength and is commonly used in products such as ropes, clothing, and parachutes. Polyester is widely used in clothing, home furnishings, and industrial applications like tire reinforcements and plastic reinforcements. Both nylon and polyester have their unique uses and are not necessarily designed to be ultra-fine like microfibers.