fontanelle

 
Pronunciation: /ˌfɒntəˈnɛl/
(US fontanel)

noun

  • a space between the bones of the skull in an infant or fetus, where ossification is not complete and the sutures not fully formed. The main one is between the frontal and parietal bones.

Origin:

mid 16th century (denoting a hollow of the skin between muscles): from French, from modern Latin fontanella, from an Old French diminutive of fontaine (see fountain). The current sense dates from the mid 18th century