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: Pollen consists of tiny grains that are the male gametes of plants. 
Sentence2: The tiny grains of pollen from plants are the ova and spermatozoa.

tiny