convection

n. circulation of heat; thermal conduction, transmission of heat by circulatory movement in a fluid or gas that results in areas of different temperatures and distinctive densities which rise and fall in reaction to gravity (Physics); conveying, act of transmitting, act of transporting; (Meteorology) upright movement of heat in enormous motion inside the atmosphere

Convection in the most general terms refers to the movement of currents within fluids (i.e. liquids, gases and rheids). Convection is one of the major modes of heat and mass transfer. In fluids, convective heat and mass transfer take place through both diffusion – the random Brownian motion of individual particles in the fluid – and by advection, in which matter or heat is transported by the larger-scale motion of currents in the fluid. In the context of heat and mass transfer, the term "convection" is used to refer to the sum of advective and diffusive transfer.
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Convection /con·vec·tion/ the act of conveying or transmission, specifically transmission of heat in a liquid or gas by bulk movement of heated [more]Convection - Community and Resources

Noun
1. the transfer of heat through a fluid (liquid or gas) caused by molecular motion
(hypernym) temperature change
2. (meteorology) the vertical movement of heat or other properties by massive motion within the atmosphere
(hypernym) natural process, natural action, action, activity
(derivation) convect
(classification) meteorology

(n.)
The act or process of conveying or transmitting.
  

(n.)
A process of transfer or transmission, as of heat or electricity, by means of currents in liquids or gases, resulting from changes of temperature and other causes.