Fontenelle

Part of speech: noun

Definitions

1. The soft membranous gap between the bones of a baby's skull where the bones have not yet fused together
2. A tender, pliable area on the top of a newborn's head where the cranial plates have not yet closed
3. The open space at the junction of the skull bones in an infant, covered by a tough membrane until ossification

Etymology: A baby's soft spot is named after a little fountain. The anatomical term comes from French "fontanelle," a diminutive of "fontaine," meaning "fountain" or "spring." The image is most likely the visible pulse beneath the membrane, which seems to rise and fall like water welling up from a spring. The French word itself is borrowed from Italian "fontanella," a diminutive of "fontana," which also meant "fountain." Romance medical writers adopted the image, and English took the term from French in early modern anatomical writing. The spelling "fontenelle," used in your request, is a variant of the same word, influenced by the French form. Both spellings refer to the same gap between the skull bones.

Synonyms: fontanel, soft spot