to introduce (something additional or extraneous) between other things or parts; interject; interpose; intercalate.

Mathematics . to insert, estimate, or find an intermediate term in (a sequence).

to alter (a text) by the insertion of new matter, esp. deceptively or without authorization.

to insert (new or spurious matter) in this manner.

to make an interpolation.

verb

erase , remove , subtract

verb

admit , annex , append , enter , fill in , include , inject , insert , insinuate , intercalate , interjaculate , interject , interlope , interpose , introduce , intrude , throw in , interlard , add , alter , change , estimate , foist