interpolate

transitive verb interpolated, interpolating

1. to alter, enlarge, or corrupt (a book or manuscript, etc.) by putting in new words, subject matter, etc.
2. to insert between or among others; specif., to insert (a word or words) in a text
3. Math. to estimate (a missing functional value) by taking a weighted average of known functional values at neighboring points, as in estimating a specific, missing intermediate value on a table, esp. a logarithmic or trigonometric table

intransitive verb