The greeting of the hands pressed together was originally developed in India, and is called namaste.
It means "I bow down to you." There is another word in Sanskrit, anjali, which identifies the same
greeting between people, and it means "divine offering." Combining them, the ever prevalent
exchange widely practiced in the East many times is translated as "I bow down to the divine in you."

In China, this greeting of palms held together, used historically mainly by Buddhists, is called
hezhang--the characters are shown below.  

Interestingly enough, the name for the Chinese Zen masters is
heshang.  This is pronounced almost
the same as the name for the folded hands greeting--
hezhang--but they are two different
characters.  The connection here is obvious.  It is a very good example of how the Chinese create
and play with their language.  You can see the character
zhang (palm) is a "sound-meaning"
combo--the top part of the character is the same as the 'shang' in
heshang, compressed. This is the
sound component. The bottom part is the ideogram for hand in Chinese--
shou. This is the meaning
part.

The Japanese use the same characters for both words--but pronounce them differently.  Hezhang
becomes "gassho" in Japanese (for the hand together greeting--namaste).  And Heshang becomes
Osho--at least in the Zen and Pure Land Buddhist Sects of Japan.  In the Tendai Sect it is
pronounced "Kasho", and in the Shingon Sect (derived from Tibetan Buddhism) it is pronounced
"Washo."

A little confusing maybe?  Sure...welcome to the Far East.

It looks like the derivation of the word Osho may come more from the original word for the palms
together greeting than from the usually accepted derivation of
upadhyaya (or even, acharya), both
Indian words for 'teachers'.  Very possibly all the words were created nearly simultaneously, maybe
on parallel tracks.   
Namaste and beyond...the continuing search for Osho....
                     oshobob  The Living Workshop                                         
                                      Namaste....What is an Osho?