Since it is a Latin word the proper plural rendering would be "atria." Some dictionaries simply add an -s to "atrium," though it doesn't sound right.
The adjective form for the noun atrium is atrial.
Atria are singularly referred to as atrium.
Atria is plural for Atrium. You have your (rt)Atrium and (lt)Atrium
Atrium is singular - the plural is atria.
There is no plural form for the word, countries. This word itself is a plural.
The plural of diary is diaries.
The plural form of the word 'deed' is 'deeds'.
The plural form of the word atrium is atria. The atria are the two upper cavities of the heart from which blood is passed to the ventricles.
Atria is the plural for of atrium. Not the other way around.
Atria is plural for Atrium. You have your (rt)Atrium and (lt)Atrium
Atrium is singular - the plural is atria.
There is no plural form for the word, countries. This word itself is a plural.
The plural form of the word "inferno" is "infernos."
There is no plural word for if.
The plural form is data.
There is no 'plural form' of the word 'minute'. The word is both singular and plural.
The plural of diary is diaries.
The plural form for the word 'pioneer' is pioneers.
The plural form of the word "baby" is "babies."