(anatomy) An opening or entrance to a passage, particularly one at either end of the cervix, internal (to the uterus) or external (to the vagina).

An osar or esker.

(rare) Alternative form of o's.

Used to form plurals of some Hebrew and Yiddish loanwords, usually ending in -a or -ah.

plural of O

(pharmacology) a monoclonal antibody that targets bone

(non-productive) Against; facing; a combining prefix found in verbs of Latin origin.

Abbreviation of Old Saxon.

(anatomy) The pelvis.

plural of big O