magnetic tape

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A plastic tape coated with iron oxide for use in magnetic recording.

Wiktionary

1. n. A type of (usually) acrylic tape with a fine coating of magnetically sensitive material on one side, used for recording audio and other data.

GNU Webster's 1913

1. adj. (Electronics) a ribbon of plastic material to which is affixed a thin layer of powder of a material which can be magnetized, such as ferrite. Such tapes are used in various electronic devices to record fluctuating voltages, which can be used to represent sounds, images, or binary data. Devices such as audio casette recorders, videocasette recorders, and computer data storage devices use magnetic tape as an inexpensive medium to store data. Different magnetically susceptible materials are used in such tapes.
2. n. A long thin plastic ribbon coated with iron oxide or other ferromagnetic material, used to record audio or video signals digital data in the form of small magnetized regions on the tape; it is a common digital data storage medium for computer information.

WordNet 3.0

1. n. memory device consisting of a long thin plastic strip coated with iron oxide; used to record audio or video signals or to store computer information