interpolation

interpolation is a Noun

Definition:

[1] The act of introducing or inserting anything, especially that which is spurious or foreign.

[2] That which is introduced or inserted, especially something foreign or spurious. Bentley wrote a letter . . . . upon the scriptural glosses in our present copies of Hesychius, which he considered interpolations from a later hand. De Quincey.

[3] The method or operation of finding from a few given terms of a series, as of numbers or observations, other intermediate terms in conformity with the law of the series.