Extrapolate is a 19th-century coinage modeled on interpolate, from extra- ('outside, beyond') + the -polate of interpolate (from Latin interpolare, 'to refurbish, alter'). Morphologically, the form is compositional: extra- marks part of the visible structure, while the remaining element supplies the lexical base. In present use, it is used as a verb meaning "to infer or estimate beyond known data by extending a trend", so the historical material remains connected with the current sense rather than standing as bare ancestry. The wider English family includes derivatives such as extrapolation and extrapolator and related forms such as interpolate, showing how the same historical material continues to organize neighboring vocabulary. The named historical forms include Latin extra and Latin interpolare, keeping the history tied to concrete forms rather than a loose resemblance.