- The definition of thermal is something related to heat.
Long underwear is an example of something that would be described as thermal underwear.
- having to do with heat, hot springs, etc.
- warm or hot
- ☆ designating or of a loosely knitted material honeycombed with air spaces for insulation to help retain body heat: thermal underwear
Origin of thermalFrench ; from Classical Greek thermē, heat: see warm
- Of, relating to, using, producing, or caused by heat.
- Intended or designed in such a way as to help retain body heat: thermal underwear.