1 a insert (words) in a book etc., esp. to give false impressions as to its date etc. b make such insertions in (a book etc.).
2 interject (a remark) in a conversation.
3 estimate (values) from known ones in the same range.
Derivatives:
interpolation n. interpolative adj. interpolator n.
Etymology: L interpolare furbish up (as INTER-, polire POLISH(1))
Useful english dictionary. 2012.