c2h6

C2H6
    n 1: a colorless odorless alkane gas used as fuel [syn:
         {ethane}, {C2H6}]
    

Homology \Ho*mol"o*gy\, n. [Gr. ? agreement. See {Homologous}.]
   1. The quality of being homologous; correspondence; relation;
      as, the homologyof similar polygons.
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   2. (Biol.) Correspondence or relation in type of structure in
      contradistinction to similarity of function; as, the
      relation in structure between the leg and arm of a man; or
      that between the arm of a man, the fore leg of a horse,
      the wing of a bird, and the fin of a fish, all these
      organs being modifications of one type of structure.
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   Note: Homology indicates genetic relationship, and according
         to Haeckel special homology should be defined in terms
         of identity of embryonic origin. See {Homotypy}, and
         {Homogeny}.
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   3. (Chem.) The correspondence or resemblance of substances
      belonging to the same type or series; a similarity of
      composition varying by a small, regular difference, and
      usually attended by a regular variation in physical
      properties; as, there is an homology between methane,
      {CH4}, ethane, {C2H6}, propane, {C3H8}, etc., all members
      of the paraffin series. In an extended sense, the term is
      applied to the relation between chemical elements of the
      same group; as, chlorine, bromine, and iodine are said to
      be in homology with each other. Cf. {Heterology}.
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   {General homology} (Biol.), the higher relation which a
      series of parts, or a single part, bears to the
      fundamental or general type on which the group is
      constituted. --Owen.

   {Serial homology} (Biol.), representative or repetitive
      relation in the segments of the same organism, -- as in
      the lobster, where the parts follow each other in a
      straight line or series. --Owen. See {Homotypy}.

   {Special homology} (Biol.), the correspondence of a part or
      organ with those of a different animal, as determined by
      relative position and connection. --Owen.
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ethane \eth"ane\ ([e^]th"[=a]n), n. [From {Ether}.] (Chem.)
   A gaseous hydrocarbon, {C2H6}, forming a constituent of
   ordinary illuminating gas. It is the second member of the
   paraffin series, and its most important derivatives are
   common alcohol (ethyl alcohol), acetaldehyde, ether, and
   acetic acid. Called also {dimethyl}.
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