If you interpolate a comment into a conversation or some words into a piece of writing, you put it in as an addition.
例句
Williams interpolated much spurious matter...威廉斯插入了許多偽造的素材。These odd assertions were interpolated into the manuscript some time after 1400.這些奇怪的論斷是于1400年后的某個時間被加入手稿的。