1 Math. & Philos. a calculate approximately from known values, data, etc. (others which lie outside the range of those known). b calculate on the basis of (known facts) to estimate unknown facts, esp. extend (a curve) on a graph.
2 infer more widely from a limited range of known facts.
Derivatives:
extrapolation n. extrapolative adj. extrapolator n.
Etymology: EXTRA- + INTERPOLATE
Useful english dictionary. 2012.