Regex – matches the first and last characters of a word

I searched a lot, but found no help.
I would like to not only find a regular expression for matching the first (one or more) and the last character (of one or more) of any word, but must match the first and last character of any word.
Example:

read
repair

so the regex only has to match "re" and "ing", not "ad" or "pair". Also, regex does not have to match "re" and "ing" at the same time (I've dared):
redisplaying
rePairing

Well, I'm not a programmer. I have just revised the proofreading of a very large text in sublime text3 editor / windows 7. please explain it so easy.

best regards.