I have a dictionary in front of me at this very moment.  It lists
"transformation" as a definition for "hentai".

Literally, the Kanji can be taken as "strange form."  Hen means
strange or weird, "tai" is form.  I've never seen it as
"transformation," and according to a friend of mine (who is

Japanese

and lives over there), that dictionary is not correct.

This is true. You should *never* automatically assume that a
dictionary is correct, because a lot of them have clear and often
retarded errors. For instance, at one point I owned a dictionary
which listed "kane" as turtle and "kame" as metal. The defintions are
clearly reversed..."kame" is turtle and "kane" is metal. 

Point being, don't always trust a single J-E/E-J dictionary. Always
consult at least two, preferably three. 

--------------------------------------------------------------------
The three things you can count on in life:
1. Someone will be offended by your words.
2. Someone will be offended by your actions.
3. Someone will be offended by your existence.
---
The Eternal Lost Lurker
...who uses a Microsoft e-mail client, and is
damned proud of it.
EternalLostLurker@worldnet.att.net
http://www.geocities.com/Tokyo/Garden/9502

Remember, breath mints are known to help 
prevent Zakari disease.
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