My breif question is...

My breif question is as follows.
When creating an item in item master, we have to define all segments of "main category", "Sub Cat.", and so on.
but in the main description all information has to be entered manually (re-write again)...

is it possibile that this description be automatically generated through data posted in segments (main/sub category, specification etc.)?

If you are using catalog then

If you are using catalog then you can update the description by it.

Else you can do a small form personalization for the same.