One of the mysteries of the English language finally explained.
A short, wide blood vessel that connects the pulmonary artery with the aorta in fetuses and embryos of amniote vertebrates, allowing blood to bypass the non-functional lungs, and normally closing irreversibly to form a fibrous ligament soon after birth. Also: a similar connection in amphibian larvae, which may retain some degree of patency in adult life.
Early 18th century; earliest use found in Philosophical Transactions of the Royal Society of London. From post-classical Latin ductus arteriosus from classical Latin ductus + post-classical Latin arteriosus.
ductus arteriosus/ˌdʌkttəs ɑːtɪərɪˈəʊsəs/
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