A swipe card is a plastic card with a magnetic strip on it which contains information that can be read or transferred by passing the card through a special machine. They use a swipe card to go in and out of their offices. A plastic card with a magnetic strip containing encoded data that is read by passing the card through a usually slotted electronic device, used especially to make electronic transactions and to provide access to restricted or secure areas. a special plastic card that you slide through a machine in order to get into a building or open a door