What is interpolation? What is interpolation? To insert or introduce between other elements or parts.To insert (material) into a text. To insert into a conversation. See Synonyms at introduce.To change or falsify (a text) by introducing new or incorrect material.Mathematics To estimate a value of (a function or series) between two known values. To create a continuous function that incorporates (a finite set of data), such as creating a curve that passes through a fixed set of points or a surface through a fixed set of curves.To introduce estimated values of (pixel data) into a pixel array to improve the quality of an enlarged digital image.