Which is the correct shorthand - "regex" or "regexp" [closed]

Solution 1:

/regexp?/    

Solution 2:

Googlefight says regex wins, 685000 to 289000 (which is about 2.37:1).

Also, regexp is strange to say out loud because there are so few (if any?) words that end in a "-ksp" sound, but there are plenty of words that end in a "-ecks" sound.