1. To obliterate information from a storage medium, such as to clear or to overwrite.
2. In a magnetic storage medium, to remove all stored data by (a) changing the medium to an unmagnetized state or (b) changing the medium to a predetermined magnetized state.
3. In paper tape and punched card storage, to punch a hole at every punch position.
Source: from Federal Standard 1037C and from MIL-STD-188