os

n., pl., o·ra (ôr'ə, ōr'ə).
A mouth or an opening.

[Latin ōs, mouth.]

os² (ŏs)
n., pl., os·sa (ŏs'ə).
A bone.

[Latin, bone.]

os³ (ōs)
n., pl., os·ar (ō'sär').
See esker.

[Swedish ås, ridge, from Old Norse āss.]

(aws)
noun [plural ora]
A mouth or an orifice. [From Latin os (mouth)

os (aws) noun [plural ossa]
A bone. [From Latin os (bone).]
os (oas) noun [plural osar]
An esker: a long, serpentine ridge of gravel formed by a stream flowing in or under a glacial ice sheet. [From Swedish ås (ridge).]
It also appears as an abbreviation in many fields, including Chemistry: Os - symbol for the element osmium Computing: OS - Operating System Pharmacy: OS - left eye (from Latin oculus sinister) Linguistics: OS - Old Saxon

Usage
"Naturally, the students couldn't resist testing the teachers' knowledge. 'You'd better slow down,' they would tell some unsuspecting pedagogue, 'or you might fall and break your os.'" — D.L. Stanley; I Hope This Doesn't Effectuate Your Dudgeon; Atlanta Inquirer (Georgia); Nov 16, 1996.

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p1. ora

The mouth or any mouth-like opening.

[L.] oculus sinister (left eye).

os	Mac Os
Airstick Os	Os X