Interpolate

v. t.
  1. To renew; to carry on with intermission.
  2. To alter or corrupt by the insertion of new or foreign matter; especially, to change, as a book or text, by the insertion of matter that is new, or foreign to the purpose of the author.
  3. (Math.) To fill up intermediate terms of, as of a series, according to the law of the series; to introduce, as a number or quantity, in a partial series, according to the law of that part of the series; to estimate a value at a point intermediate between points of knwon value. Compare extrapolate.