expansion card
noun[C]
ITukusaboardcoveredwithsmallmetalelectricalconnectionsthatcreateone or morecircuitsand that can beconnectedto themaincircuitboardof acomputerso that it can do more things:
Installing awireless(or any other)networkusuallymeansopeningyourdesktopPC toplugin anexpansioncard.
See also
USB