fontanelle

British  

/ ˌfɒntəˈnɛl /

noun

1. anatomy any of several soft membranous gaps between the bones of the skull in a fetus or infant

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Etymology

Origin of fontanelle

C16 (in the sense: hollow between muscles): from Old French fontanele , literally: a little spring, from fontaine _fountain

Explanation

A fontanelle is the soft spot on a baby's head where the skull bones haven't finished growing and fusing together. Even though the fontanelle seems delicate, it's actually quite sturdy and protective. The fontanelle allows a newborn baby's brain to continue growing, while the skull expands more slowly. It also means the bones of the skull can flex a bit when the baby is born — in other words, it can compress as it's squeezed through the birth canal without damaging the baby's head. As babies grow, the fontanelle begins to close. The Old French root of fontanelle, fontaine, means "hollow in the earth where a spring arises."

Example Sentences

But after noticing that Molly's fontanelle - the soft spot on the top of her head - was bulging when she was 12 weeks, a doctor in A&E diagnosed a large brain tumour.

From BBC • Sep. 30, 2025

America also has a spot softer than a newborn’s fontanelle for shallow nonsense.

From Salon • Dec. 17, 2023

America also has a spot softer than a newborn’s fontanelle for shallow nonsense.

From Salon • Dec. 17, 2023

The incubator, the tube in our son’s nose, the tender fontanelle of his crown – these were the only things I allowed myself to care about.

From The Guardian • Apr. 9, 2019

At six months of age the fontanelle is somewhat larger than it was at birth because the brain expands faster than the boney matter deposited around the edges in the skull bones.

From Mother's Remedies Over One Thousand Tried and Tested Remedies from Mothers of the United States and Canada by Ritter, Thomas Jefferson