ostium primum

noun
ostium pri·​mum | \ -ˈprī-məm How to pronounce ostium primum (audio) \

Medical Definition of ostium primum

: an opening between the two embryonic atria of the heart that exists temporarily at the bottom of the developing interatrial septum and is eventually closed off by this septum and replaced by the ostium secundum

Learn More About ostium primum

Dictionary Entries Near ostium primum

ostium

ostium primum

ostium secundum

See More Nearby Entries 

Cite this Entry

“Ostium primum.” Merriam-Webster.com Medical Dictionary, Merriam-Webster, https://www.merriam-webster.com/medical/ostium%20primum. Accessed 25 Oct. 2021.

Style: MLA
MLACheck Mark Icon ChicagoCheck Mark Icon APACheck Mark Icon Merriam-WebsterCheck Mark Icon

WORD OF THE DAY

Test Your Vocabulary

Dog Words Quiz

  • shiba puppy more or less demanding cuddles
  • Which of the following animals has a dog in its etymology?
Name That Thing

Test your visual vocabulary with our 10-question challenge!

TAKE THE QUIZ
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!