1. [n]  the musical interval between one note and another five notes away from it
2. [n]  a quantity of liquor equal to one fifth of a United States gallon
3. [n]  a fifth part
4. [n]  position five in a countable series of things; "he was fifth out of several hundred runners"
5. [adj]  coming next after the fourth and just before the sixth in position

1. \Fifth\, a. [OE. fifte, fifthe, AS. f[=i]fta. See {Five}.]
   1. Next in order after the fourth; -- the ordinal of five.
   
   2. Consisting of one of five equal divisions of a thing.
   
   {Fifth monarchy men} (Hist.), a fanatical sect in England, of
      the time of the commonwealth, who maintained that there
      would be a fifth universal monarchy, during which Christ
      would reign on earth a thousand years.
   
   {Fifth wheel}, a horizontal wheel or segment above the fore
      axle of a carriage and beneath the body, forming an
      extended support to prevent careening.
   
   
   
   

2. \Fifth\, n.
   1. The quotient of a unit divided by five; one of five equal
      parts; a fifth part.
   
   
   
   2. (Mus.) The interval of three tones and a semitone,
      embracing five diatonic degrees of the scale; the dominant
      of any key.
   
   

An enhanced version of FORTH. M.S. Dissertation, Cliff Click <cliff@cs.rice.edu>, Texas A&M, 1985. Available from the Software Construction Co, (409)696-5432.