Thermal underwears are an essential part of winter clothing, especially when venturing out in cold temperatures. The term "thermal underwears" can be replaced with various synonyms, such as long johns, base layers, thermals, and insulating underwear. These words describe the same garment that provides warmth and protection against freezing temperatures. Other related terms you can use include leggings, tights, body liners, and even fleece-lined pants. These words enable you to express the same idea of protection and warmth effectively. So, whether you're looking to buy thermal underwear or describing this critical piece of winter clothing, using synonyms can make your language more interesting and varied.