[1] : WordNet (r) 2.0

sonny
     n : a male child a familiar term of address to a boy syn: cub,
          lad, laddie, sonny boy
see also:
cub lad laddie sonny boy 

[2] : Moby Thesaurus II by Grady Ward, 1.0

38 moby thesaurus words for "sonny":
   boy, bub, bubba, buck, bud, buddy, child, colt, cub, daughter,
   descendant, fellow, fledgling, foster child, grandchild,
   granddaughter, grandson, heiress, hobbledehoy, lad, laddie,
   manchild, master, muchacho, offspring, pup, puppy, schoolboy,
   scion, son, son and heir, sonny boy, stepchild, stepdaughter,
   stepson, whelp, young man, youth

Sonny >> S Words
Sonny, definition of term: Sonny
sonny_pag1.html

Sonny Boy >> S Words
Sonny Boy, definition of term: Sonny Boy
sonny+boy_pag1.html