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: Rocket propellants are the fuels and the oxidizers carried by the rocket for propulsion. 
Sentence2: oxidizers are used for flying a spacecraft.

oxidizers