os

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A bone.
• noun A mouth or an opening.

from The Century Dictionary.

• noun In chem., the symbol for osmium.
• noun In geology, a Swedish term for certain elongated ridges of detrital material, generally considered to be of glacial origin, or in some not yet clearly explained way connected with the former presence of ice in the region where they occur.
• noun Same as os extrascapulare.
• noun An abbreviation of the Latin Ordo Sancti Augustini, Order of St. Augustine.
• noun A mouth; a passage or entrance into any place: an anatomical term; specifically, the mouth of the womb.
• noun An abbreviation of the Latin Ordo Sancti Benedicti, Order of St. Benedict.
• An abbreviation of the Latin Ordo Sancti Francisci, Order of St. Francis.
• noun Bone; a bone.

from the GNU version of the Collaborative International Dictionary of English.

• noun A bone.
• noun A mouth; an opening; an entrance.
• noun (Geol.) One of the ridges of sand or gravel found in Sweden, etc., supposed by some to be of marine origin, but probably formed by subglacial waters. The osar are similar to the kames of Scotland and the eschars of Ireland. See eschar.
• noun (Chem.) The chemical symbol for the element osmium.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun An osar or esker.
• noun rare, medicine Bone.
• noun rare A mouth; an opening.
• noun In particular, either end of the cervix, internal (to the uterus) or external (to the vagina).

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the left eye
• noun a mouth or mouthlike opening
• noun a hard brittle blue-grey or blue-black metallic element that is one of the platinum metals; the heaviest metal known
• noun rigid connective tissue that makes up the skeleton of vertebrates
• noun (computer science) software that controls the execution of computer programs and may provide various services