Wildcard character

The term wildcard character has the following meanings:

Telecommunication

In telecommunications, a wildcard character is a character that may be substituted for any of a defined subset of all possible characters.

In high-frequency (HF) radio automatic link establishment, the wildcard character "?" may be substituted for any one of the 36 characters, "A" through "Z" and "0" through "9."
Whether the wildcard character represents a single character or a string of characters must be specified.

Computing

In computer (software) technology, a wildcard character can be used to substitute for any other character or characters in a string.

The asterisk (*) usually substitutes as a wildcard character for any zero or more characters, and the question mark (?) usually substitutes as a wildcard character for any one character, as in the CP/M, DOS, Microsoft Windows and POSIX (Unix) shells. (In Unix this is referred to as glob expansion.) In SQL, the wildcard characters are percent (%) for zero or more characters, and underscore (_) for one character. In many regular expression implementations, the period (.) is the wildcard character for a single character.

Source: originally from Federal Standard 1037C and from MIL-STD-188