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: An example is H2O which shows water is made of two atoms of hydrogen stuck to one atom of oxygen. 
Sentence2: thirst is used to make an animal realize that it needs to replenish H2O in its body.

H2O