1) Add besides 2) Join as a further addition 3) To add over and above 
• (v. t.) To add over and above; to add to what has been added; to annex, as something extrinsic.
To add over and above; to add to what has been added; to annex, as something extrinsic. 'The strength of any living creature, in those external motion, is something distinct from, and superadded unto, its natural gravity.' (Bp. Wilkins) 'The peacock laid it extremely to heart that he had not the nightingale's voice superadded to the beauty of his p...
Su`per·add' transitive verb [ imperfect & past participle Superadded ; present participle & verbal noun Superadding .] [ Latin superaddere . See Super- , and Add .] To add over and above; to add to what has been add...
superadd 1. To add something onto what has already been added. 2. To add over and above; to add to what has been added.
to add over and above; join as a further addition; add besides.