Definition: Generate an overlapping word between the given two sentences. When you find the overlapping words, they don't have to match exactly, e.g., "survival" and "survive" are valid overlapping words. Little words like "the" or "of" don't count! You must generate significant words which are not the stop words.
Input: Sentence1: Light enters the eye through the pupil, and the pupil is made larger or smaller by the iris. 
Sentence2: When light goes through the pupil, the iris makes it larger or smaller.

larger