What does fontanel mean?
A fontanel is one of the soft, membranous spaces between the bones of a fetus's or infant's skull where the cranial plates have not yet grown together. Newborns have several fontanels, of which the most noticeable is the diamond-shaped anterior fontanel at the crown, typically closing between about nine and eighteen months of age, while the smaller posterior fontanel closes within the first few months. These gaps serve two vital purposes: they allow the head to mould as it passes through the birth canal, and they give the rapidly growing brain room to expand during infancy. Clinically, the fontanel is a useful diagnostic window — a bulging fontanel can indicate raised pressure inside the skull, while a sunken one may signal dehydration. The name derives from French 'fontanelle', a little fountain, an apt image since the pulse of blood vessels can be seen beating beneath the membrane. Though primarily a medical term, it appears often in parenting advice, where clinicians reassure parents that the tough membrane makes ordinary handling perfectly safe.
nounA soft, membranous gap between the bones of an infant's skull where the bony plates have not yet fused, allowing the head to compress during birth and the brain to grow rapidly after it.
- A membrane-covered gap between the unfused cranial bones of a fetus or infant, especially the diamond-shaped anterior fontanel at the top of the head.
"The paediatrician gently examined the baby's fontanel during the routine check-up."
"The nurse reassured the new mother that touching the baby's fontanel while washing its hair was perfectly safe."
"A sunken fontanel can be an early sign of dehydration in infants and warrants prompt medical attention."
Because newborns have several fontanels, the plural is common in medical writing; the variant 'fontanelle(s)' is preferred in British English.
"At birth, the infant had six fontanels, though only two were readily palpable."
A baby's skull starts life in pieces — six plates separated by 'soft spots' called fontanels that let the head squeeze through the birth canal and expand as the brain nearly triples in size in the first year.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of fontanel
The word comes from the French 'fontanelle', itself derived from 'fontaine' (fountain) and ultimately from Latin 'fons', meaning spring or source. The anatomical term entered English in the late sixteenth or early seventeenth century, borrowed from French medical writing; the connection is literal, since the pulsing of veins beneath the membrane reminded early anatomists of a bubbling spring. The same Latin root gives English 'fountain' and 'font', making them distant cousins of this word about babies' skulls.
Related word forms
How fontanel is actually used
The word is almost exclusively used in medical, paediatric, and childcare contexts rather than casual conversation; it carries a neutral, clinical connotation. In American usage both 'fontanel' and the plural-like variant 'fontanelle(s)' appear, while 'fontanelle' predominates in British usage. Parents sometimes worry unduly about the soft spot, so the term frequently appears alongside reassurance in antenatal and infant-care advice.
Easily confused with fontanel
Fontanelle is simply the more common British-style variant spelling and form of the same word, referring to exactly the same anatomical structure, not a different thing.