Source : Webster's Revised Unabridged Dictionary (1913)

Interpolation \In*ter`po*la"tion\, n. [L. interpolatio an
   alteration made here and there: cf. F. interpolation.]
   1. The act of introducing or inserting anything, especially
      that which is spurious or foreign.

   2. That which is introduced or inserted, especially something
      foreign or spurious.

            Bentley wrote a letter . . . . upon the scriptural
            glosses in our present copies of Hesychius, which he
            considered interpolations from a later hand. --De
                                                  Quincey.

   3. (Math.) The method or operation of finding from a few
      given terms of a series, as of numbers or observations,
      other intermediate terms in conformity with the law of the
      series.

Source : WordNet®

interpolation
     n 1: a message (spoken or written) that is introduced or
          inserted; "with the help of his friend's interpolations
          his story was eventually told"; "with many insertions in
          the margins" [syn: {insertion}]
     2: (mathematics) calculation of the value of a function between
        the values already known
     3: the action of interjecting or interposing an action or
        remark that interrupts [syn: {interjection}, {interposition},
         {interpellation}]

Source : Free On-Line Dictionary of Computing

interpolation
     
         A mathematical procedure which
        estimates values of a {function} at positions between listed
        or given values.  Interpolation works by fitting a "curve"
        (i.e. a function) to two or more given points and then
        applying this function to the required input.  Example uses
        are calculating {trigonometric functions} from tables and
        audio waveform sythesis.
     
        The simplest form of interpolation is where a function, f(x),
        is estimated by drawing a straight line ("linear
        interpolation") between the nearest given points on either
        side of the required input value:
     
        	f(x) ~ f(x1) + (f(x2) - f(x1))(x-x1)/(x2 - x1)
     
        There are many variations using more than two points or higher
        degree {polynomial} functions.  The technique can also be
        extended to functions of more than one input.
     
        (1997-07-14)