The Collaborative International Dictionary of English v.0.48:

Pediatrics \Ped`i*at"rics\, n.
   That branch of medical science which treats of the hygiene
   and diseases of infants and children.

   Syn: paediatrics.
        [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

pediatrics
    n 1: the branch of medicine concerned with the treatment of
         infants and children [syn: pediatrics, paediatrics,
         pediatric medicine, pedology]