The Collaborative International Dictionary of English v.0.48:

Nursling \Nurs"ling\, n. [Nurse + -ling.]
   One who, or that which, is nursed; an infant; a fondling.
   [1913 Webster]

         I was his nursling once, and choice delight. --Milton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

nursling
    n 1: an infant considered in relation to its nurse [syn:
         nursling, nurseling, suckling]