The Collaborative International Dictionary of English v.0.48:

Ketone \Ke"tone\ (k[=e]"t[=o]n), n. [Cf. Acetone.] (Chem.)
   One of a large class of organic substances resembling the
   aldehydes, obtained by the distillation of certain salts of
   organic acids and consisting of carbonyl (CO) united with
   two hydrocarbon radicals. In general the ketones are
   colorless volatile liquids having a pungent ethereal odor.
   [1913 Webster]

   Note: The ketones are named by adding the suffix-one to the
         stems of the organic acids from which they are
         respectively derived; thus, acetic acid gives acetone;
         butyric acid, butyrone, etc.
         [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Acyl \Ac"yl\, n. [Acid + -yl.] (Org. Chem.)
   An acid radical, as acetyl, malonyl, or benzoyl. An acyl
   radical can be depicted as R-CO-, where -CO- is the
   carbonyl group, and R is the group that characterizes the
   acyl moiety.
   [Webster 1913 Suppl. +PJC]

The Collaborative International Dictionary of English v.0.48:

Carbonic \Car*bon"ic\, a. [Cf. F. carbonique. See Carbon.]
   (Chem.)
   Of, pertaining to, or obtained from, carbon; as, carbonic
   oxide.
   [1913 Webster]

   Carbonic acid (Chem.), an acid HO.CO.OH, not existing
      separately, which, combined with positive or basic atoms
      or radicals, forms carbonates. In common language the term
      is very generally applied to a compound of carbon and
      oxygen, CO2, more correctly called carbon dioxide. It
      is a colorless, heavy, irrespirable gas, extinguishing
      flame, and when breathed destroys life. It can be reduced
      to a liquid and solid form by intense pressure. It is
      produced in the fermentation of liquors, and by the
      combustion and decomposition of organic substances, or
      other substances containing carbon. It is formed in the
      explosion of fire damp in mines, and is hence called
      after damp; it is also know as choke damp, and
      mephitic air. Water will absorb its own volume of it,
      and more than this under pressure, and in this state
      becomes the common soda water of the shops, and the
      carbonated water of natural springs. Combined with lime it
      constitutes limestone, or common marble and chalk. Plants
      imbibe it for their nutrition and growth, the carbon being
      retained and the oxygen given out.

   Carbonic oxide (Chem.), a colorless gas, CO, of a light
      odor, called more correctly carbon monoxide. It is
      almost the only definitely known compound in which carbon
      seems to be divalent. It is a product of the incomplete
      combustion of carbon, and is an abundant constituent of
      water gas. It is fatal to animal life, extinguishes
      combustion, and burns with a pale blue flame, forming
      carbon dioxide.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Carbonyl \Car"bon*yl\, n. [Carbon + -yl.] (Chem.)
   The radical (=CO), occuring, always combined, in many
   compounds, as the aldehydes, the ketones, urea, carbonyl
   chloride, etc.
   [1913 Webster]

   Note: Though denoted by a formula identical with that of
         carbon monoxide, it is chemically distinct, as carbon
         seems to be divalent in carbon monoxide, but
         tetravalent in carbonyl compounds.
         [1913 Webster]

   Carbonyl chloride (Chem.), a colorless gas, COCl2, of
      offensive odor, and easily condensable to liquid. It is
      formed from chlorine and carbon monoxide, under the
      influence of light, and hence has been called phosgene,
      or phosgene gas; -- called also carbon oxychloride. It
      is used in chemical synthesis, and was also used as a
      poison gas in World War I.
      [1913 Webster +PJC]

The Collaborative International Dictionary of English v.0.48:

Co \Co\ n.
   the chemical formula for cobalt, a ferromagnetic metal of
   atomic number 27.

   Syn: cobalt, atomic number 27.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

Co- \Co-\ (k[-o]-).
   A form of the prefix com-, signifying with, together, in
   conjunction, joint. It is used before vowels and some
   consonants. See Com-.
   [1913 Webster]

V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

CO
       Connection Oriented (CL)


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

CO
       Check Out (RCS)


Bouvier's Law Dictionary, Revised 6th Ed (1856):

CO. A prefix or particle in the nature of an inseparable proposition,
signifying with or in conjunction. Con and the Latin cum are equivalent, as,
co-executors, co-obligor. It is also used as an abbreviation for company as,
John Smith & Co.