Definition from Wiktionary, the free dictionary
Alternative forms 
- The process of conveying something.
- (physics) The transmission of heat in a fluid or gas by the circulation of currents.
- (meteorology) The vertical movement of heat and moisture, especially by updrafts and downdrafts in an unstable air mass. The terms convection and thunderstorm are often used interchangeably, although thunderstorms are only one form of convection. Towering cumulus clouds are visible forms of convection.
Coordinate terms 
Derived terms 
process of conveying something
transmission of heat by the circulation of currents
vertical movement of heat and moisture
See also 
- “convection” in Douglas Harper, Online Etymology Dictionary (2001).