Regex 'or' operator avoid repetition

Question

How can I use the or operator while not allowing repetition? In other words the regex:

(word1|word2|word3)+

will match wo

Answer 1

Byers' solution is too hard coded and gets quite cumbersome after the letters increases.. Why not simply have the regex look for duplicate match?

([^\d]+\d)+(?=.*\1)

If that matches, that match signifies that a repetition has been found in the pattern. If the match doesn't work you have a valid set of data.