Xt> (Or "Kleene closure", named after Stephen Kleene) The postfiX "*" operator used in regular eXpressions, EXtended Backus-Naur Form, and similar formalisms to specify a match for zero or more occurrences of the preceding eXpression. For eXample, the regular eXpression "be*t" would match the string "bt", "bet", "beet", "beeeeet", and so on. (2000-07-26)