Any ordinary, nonremovable (or fixed) hard disk drive. The name originates from a particular IBM drive in the 1960s that had 30MB of fixed and 30MB of removable storage. This 30-30 drive matched the caliber figure for a popular series of rifles made by Winchester, so the slang term Winchester was applied to any fixed-platter hard disk.
In computing, a small hard-disc drive commonly used with microcomputers; Winchester disc has become synonymous with hard disc.