what's the pattern on "Abba"? I thought it was just to exclude doubled letters but I have doubles on two words on the left hand side as well (noisefully and effusive, in case the word lists are the same)
^((?!([aeiou])([^aeiou])\3\2).)*$
^((?!(.)(.)\3\2).)*$ ef|^((?!(.)\2).)*$
^(.)(.).*\2\1$haha