You can use the page "Note", for your description

:)

Solve !!

1.go to any product template as debug mode

2.click on bug on right corner -> edit form view

3.add this code 

<group name="description">

     <separator string="Description for Product" colspan="4"/>

     <field name="description" colspan="4" nolabel="1" placeholder="This note will be displayed on product description" modifiers="{}"/>

    </group>

But these descriptions in the Note tab are specifically for quotations (description_sale), vendors (description_purchase), and pickings (description_picking) .

I need to give an internal description to the product itself like you see in Odoo 8. The field name of this description field is "description". I can see this field under the setting menu (product.template) but it's not shown in the form. Anyone can help me out?

Check the notes tab.