In some bibliographic databases and search engines, the search software allows the user to insert a special character in the middle of a search term used in a keyword(s) search, to retrieve records or sites containing words with any character or no character in the position, useful for retrieving irregular plurals and variant spellings of a word. The wildcard symbol is not standardized. Users are advised to read the help screen(s) in an unfamiliar interface to see if wildcard is available and, if so, what symbol is used. See also: truncation.

Examples: wom#n or wom?n to retrieve records containing woman or women colo#r or colo?r to retrieve records containing color or colour

In computing, a symbol available in most operating systems and application programs (usually the asterisk), which can be used in a filename to identify multiple files and directories, for example, letter*.doc to retrieve all the "doc" files with filenames beginning with "letter." Most word processing applications also allow the user to employ wildcard in text searches.

From ODLIS, Online Dictionary for Libary and Information Science by Joan M. Reitz
http://lu.com/odlis/about.cfm