We don't have synonyms for regex yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are remex, regen and reger.
(n) :
(computing) Clipping of regular expression. [(computing theory) A concise description of a regular formal language with notations for concatenation, alternation, and iteration (repetition) of subexpressions.]
(n) :
(computing) Clipping of regular expression. [(computing theory) A concise description of a regular formal language with notations for concatenation, alternation, and iteration (repetition) of subexpressions.]