noun
definition
A small opening or orifice, as in a body organ or passage.
definition
Any of the small openings or pores in a sponge.
definition
The mouth of a river.
Examples of ostium in a Sentence
Two or three membranous flaps, held by numerous chordae tendineae, form a true mitral valve, and allow the blood to pass through the left ostium atrioventriculare.
The small opening among the fimbriae by which the tube communicates with the peritoneal cavity is known as the ostium abdominale, and from this the lumen of the tube runs from four to four and a half inches, until it opens into the cavity of the uterus by an extremely small opening.
Aglossa, - Eustachian tubes united into a single ostium pharyngeum; no tongue.
It was the first colony ever founded by Rome - according to the Romans themselves, by Ancus Martius - and took its name from its position at the mouth (ostium) of the river.