What is sweatpants? How to use in English

The origins of the word "sweatpants" are unclear, but it's believed to have emerged in the United States in the late 19th or early 20th century. The word "sweat" in this context likely refers to the slang term "sweat" meaning exercise or physical activity, rather than perspiration. During the 1930s and 1940s, athletic wear manufacturers like Champion and Russell Athletic began producing loose-fitting, cotton-blend pants designed for exercise and comfort. These early sweatpants were marketed as a more relaxed, casual alternative to traditional athletic wear. The term "sweatpants" gained popularity in the 1960s and 1970s as the fashion and athletic industries merged, and sweatpants became a staple in many people's wardrobes. Today, the term is widely recognized and is often used to describe loungewear, casual wear, and active wear alike.