挿入 （ソウニュウ） insertion, incorporation, infixing

挿話 （ソウワ） episode, side story, story within a story, aside, anecdote

外挿 （ガイソウ） extrapolation

内挿 （ナイソウ） interpolation

挿す （さす） to insert, to put in, to plant (a cutting), to strike, to arrange (flowers), to wear (a sword) in one's belt, to shut, to close, to lock, to fasten

挟む （はさむ） to hold between (e.g. one's fingers, chopsticks), to grip (from both sides), to put between, to sandwich between, to insert, to interpose, to catch (e.g. a finger in a door), to trap, to pinch, to insert (e.g. a break into proceedings), to interpose (e.g. an objection), to interject, to throw in (e.g. a joke), to be on either side of (a road, table, etc.), to have between each other, to be across (a street, river, etc.), to harbour (feelings), to cast (e.g. doubt)