13 letters · 15 points in Scrabble
noun a message (spoken or written) that is introduced or inserted
noun (mathematics) calculation of the value of a function between the values already known
noun the action of interjecting or interposing an action or remark that interrupts
originFrom French interpolation, from Latin interpolatio. Morphologically interpolate + -ion.
Etymology from Wiktionary, CC BY-SA 3.0