Wiktionary
magnetic stripe
n. A band of magnetic material in which tiny iron-based particles are used for data storage, used on swipecards.
WordNet
magnetic stripe
n. a short strip of magnetic tape attached to a credit card or debit card; the magnetic stripe contains data that will tell a reading device who you are and what your account number is, etc.
Usage examples of "magnetic stripe".
On the door was the lettering, UN STAFF ONLY The officer took out a plastic, coded key card and swiped it through the magnetic stripe reader.
There was nothing imprinted on it at all, not even an arrow or a magnetic stripe.