SINCE 1828

An Encyclopædia Britannica Company

Medical Dictionary

fossa ovalis

noun fossa oval·is \ -ō-ˈva-ləs , -ˈvā- , -ˈvä- \

medical Definition of fossa ovalis

1 : a depression in the septum between the right and left atria that marks the position of the foramen ovale in the fetus

2 : saphenous opening

Seen and Heard

What made you want to look up fossa ovalis? Please tell us where you read or heard it (including the quote, if possible).

show

WORD OF THE DAY

riposte

play

a quick and clever reply

Words at Play

Noun + Verb Insult Generator

A collection of obscure put-downs

alt-5b0834b915e3f

'Judicial' v. 'Judicious': We'll Settle The Case

A judgment call

alt-5b06e60511014

'Deprived' vs. 'Depraved'

Nobody wants to be either.

alt-5b05d8545c817

'Folksonomy': Let’s Get Organized

Tag the way you want to tag.

Ask the Editors

video-ghost-words

Ghost Word

The story of an imaginary word that managed to sneak past our editors and enter the dictionary.

2017 Word of the Year: Behind the Scenes

How we chose 'feminism'

video-literally

Literally

How to use a word that (literally) drives some people nuts.

video-his-or-her

Is Singular 'They' a Better Choice?

The awkward case of 'his or her'

Word Games

May 2018 Words of the Day Quiz

We’re already at the end of May?!

Take the quiz

Words Used by Nabokov Quiz

How familiar are you with Nabokov’s unfamiliar vocabulary?

Take the quiz

Spell It

Can you spell these 10 commonly misspelled words?

Take the quiz

Add Diction

Build a chain of words by adding one letter at a time.

Play the game