
Latin, meaning: entrance, door.
Found on
http://archives.nd.edu/ooo.htm

mouth-like opening
Found on
http://phrontistery.info/o.html

• (n.) An opening; a passage.
Found on
http://thinkexist.com/dictionary/meaning/ostium/

(from the article `human cardiovascular system`) ...arteries originate from the right and left aortic sinuses (the sinuses of Valsalva), which are bulges at the origin of the ascending aorta ... ...air sinuses, four on each side, are cavities in the bones that adjoin the nose. They are outgrowths from the nasal cavity and retain their ....
Found on
http://www.britannica.com/eb/a-z/o/37

(os´te-әm) Latin word meaning an opening or orifice. adj., os´tial., adj.
Found on
http://www.encyclo.co.uk/local/21001
Os'ti·um noun ;
plural Ostia . [ Latin ]
(Anat.) An opening; a passage.
Found on
http://www.encyclo.co.uk/webster/O/39

Type: Term Pronunciation: os′tē-ŭm, -ă Definitions: 1. A small opening, especially one of entrance into a hollow organ or canal.
Found on
http://www.medilexicon.com/medicaldictionary.php?t=63894

os, mouth.
Found on
https://aclandanatomy.com/Glossary.aspx

Latin = a door, an opening, an orifice.
Found on
https://www.encyclo.co.uk/local/21450

a small opening or orifice, as at the end of the oviduct. · one of the tiny holes in the body of a sponge.
Found on
https://www.infoplease.com/dictionary/ostium

entrance, door.
Found on
https://www.math.ubc.ca/~cass/frivs/latin/latin-dict-full.html
No exact match found.