Still life photography is a representation of chiefly inanimate objects and the ability to put those objects together to create a pleasing image.  Still life images are typically constructed on a table top.
Tabletops are any photographic setup which is made on a tabletop.  No one says how big – or small - the table must be – it’s whatever table YOU can manage.  Just remember that.
http://dictionary.reference.com/  says the American Heritage Dictionary defines “still life” as:
1. Representation of inanimate objects, such as flowers or fruit, in painting or
     photography.
2. A painting, picture, or photograph of inanimate objects.