Joseph = "let him add"
derivation: of Hebrew origin (03130)
http://bible.crosswalk.com/Lexicons/Greek/grk.cgi?number=2501&version=kjv

(03130)
Joseph = "Jehovah has added"
derivation: future of (03254)
http://bible.crosswalk.com/Lexicons/Hebrew/heb.cgi?number=3130&version=kjv

(03254)
1] to add, increase, do again
   1.a] (Qal) to add, increase, do again
   1.b] (Niphal)
       1.b.1] to join, join oneself to
       1.b.2] to be joined, be added to
   1.c] (Hiphil)
       1.c.1] to cause to add, increase
       1.c.2] to do more, do again
http://bible.crosswalk.com/Lexicons/Hebrew/heb.cgi?number=3254&version=kjv