To introduce (something) between other things; especially to insert (possibly spurious) words into a text.
During the course of processing some data, and in response to a directive in that data, to fetch data from a different source and process it in-line along with the original data.
To estimate the value of a function between two tabulated points.
To include (e.g. a certain word or phrase) into a sentence discreetly
To enter discreetly
To play a subtle pass into someone in a goalscoring position.