what is the longest word that can be arranged like "tattoo=aoottt?

Question

that is a ten letter word that can be arranged like 1 2 3 4

Answer 1

SERENENESS = R-NN-EEE-SSSS

Answer 2

The longest of these "reverse palindromes" (also called "semiordnilap", "reverse anagram") are the following three EIGHT-letter sets (there are none as long as 10 letters). . .the best of which is the first, since it consists of two words everyone acknowledges as real:

desserts – stressed
dioramas – samaroid
redrawer – rewarder

There are many shorter sets. For a good list, check out:
http://en.allexperts.com/e/s/se/semordnilap.htm