The act of conducting or carrying out (business, negotiations, plans).

A deal or business agreement. (Can we add an example for this sense?)

An exchange or trade, as of ideas, money, goods, etc.

(finance) The transfer of funds into, out of, or from an account.

(computing) An atomic operation; a message, data modification, or other procedure that is guaranteed to perform completely or not at all (e.g. a database transaction).

(especially in plural) A record of the proceedings of a learned society.

(transactional analysis) A social interaction.