1874, a back-formation from extrapolation by analogy of interpolate. Said in early references to be an expression of Sir George Airy (1801-1892), English mathematician and astronomer. Related: Extrapolated; extrapolating.
extrapolate in Science
extrapolate
(ĭk-strāp'ə-lāt') To estimate the value of a quantity that falls outside the range in which its values are known.