O \O\ ([=o]), n.; pl. O's or Oes ([=o]z).
   1. The letter O, or its sound. "Mouthing out his hollow oes
      and aes." --Tennyson.
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   2. Something shaped like the letter O; a circle or oval.
      "This wooden O [Globe Theater]". --Shak.
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   3. A cipher; zero. [R.]
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            Thou art an O without a figure.       --Shak.
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	Os \Os\, n. (Chem.)
   The chemical symbol for the element osmium.
   [PJC]

	

	Os \Os\, n.; pl. Ossa. [L.]
   A bone.
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	Os \Os\, n.; pl. Ora. [L.]
   A mouth; an opening; an entrance.
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	Os \Os\, n.; pl. Osar. [Sw. [*a]s ridge, chain of hills, pl.
   [*a]sar.] (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.
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	os
     n 1: a mouth or mouthlike opening
     2: a hard brittle blue-gray or blue-black metallic element that
        is one of the platinum metals; the heaviest metal known
        [syn: osmium, atomic number 76]
     3: (computer science) software that controls the execution of
        computer programs and may provide various services [syn: operating
        system]
     4: the left eye [syn: oculus sinister]
     5: rigid connective tissue that makes up the skeleton of
        vertebrates [syn: bone]
     [also: ossa (pl), osar (pl), ora (pl)]

	

	OS
     Operating System

	

	OS /O-S/ 1. [Operating System] n. An abbreviation heavily used in
   email, occasionally in speech. 2. n. obs. On ITS, an output spy. See
   "OS and JEDGAR" in Appendix A.

	

	OS
     
        1. operating system.
     
        2. [obsolete, ITS], an output spy.  See "OS and JEDGAR".
     
        3.  An operating system from IBM for
        their System/360 line of hardware announced in 1964.  OS was
        planned with several flavours that were supposed to be
        compatible.  OS was late, memory hungry and not able to reach
        the marketing objectives of IBM for the 360/30, the planned
        successor of the IBM 1401.  IBM then decided to design a new
        operating system for the low end machines which they called
        DOS/360.
     
        [Jargon File]
     
        (1997-09-22)