What is another word for thermal underwear?
Pronunciation: [θˈɜːmə͡l ˌʌndəwˈe͡ə] (IPA) 
Thermal underwear, also known as long johns or base layers, are essential for those living in areas with colder climates. However, sometimes using the same word repeatedly can become monotonous. There are several synonyms that can be used interchangeably with thermal underwear such as insulated undergarments, cold-weather underwear, winter gear, and heat-trapping base layers. Each of these terms describes the same product that keeps you warm and comfortable during the colder months. Whether you prefer to use thermal underwear or any of its synonyms, the most important thing is to stay warm and cozy when temperatures plummet.
