noun
fontanel; fontanelle
Rare physiological term for the soft spot on an infant's head; the more common word is 泉門 (せんもん).
See also: 泉門
赤ちゃんのひよめきは、生後しばらくすると閉じる。
A baby's fontanel closes some time after birth.
The standard medical term for fontanel; ひよめき is a rare synonym usually written in kana.
The derivation is uncertain. The word is native Japanese, and the kanji spellings are rare ateji-like assignments.