transaction

Concise Oxford English Dictionary © 2008 Oxford University Press:
transaction/tranˈzakʃn/

▶noun

• 1 an instance of buying or selling.

  ■ the action of conducting business.

• 2 an exchange or interaction between people.

• 3 (transactions) published reports of proceedings at the meetings of a learned society.

• 4 an input message to a computer system dealt with as a single unit of work.

– derivatives
transact verb,
transactional adjective,
transactionally adverb,
transactor noun.

– origin ME (as a term in Roman Law): from late L. transactio(n-), from transigere ‘drive through’.