con ‧ vec ‧ tion /kənˈvekʃ ə n/ BrE AmE noun [uncountable] technical
[ Date: 1800-1900 ; Language: Late Latin ; Origin: convectio , from Latin convehere 'to bring together' , from com- ( ⇨ COM- ) + vehere 'to carry' ]
the movement in a gas or liquid caused by warm gas or liquid rising, and cold gas or liquid sinking