Cassette

noun

1. A small flat case containing magnetic tape on two reels, used to record and play back audio and video material.
2. Any similar small cartridge, such as for a computer disk or cassette air conditioner
3. A lightproof container for photographic film.
4. A modular DNA sequence encoding one or more genes for a single biochemical function.
5. A set of sprockets mounted onto a splined shaft on the freehub.