The Collaborative International Dictionary of English v.0.48:

Fontanelle \Fon`ta`nelle"\, n. [F.] (Anat.)
   Same as Fontanel, 2.
   [1913 Webster]

WordNet (r) 3.0 (2006):

fontanelle
    n 1: any membranous gap between the bones of the cranium in an
         infant or fetus [syn: fontanelle, fontanel, soft
         spot]