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: Hobby greenhouses used to be small glass houses or fiberglass buildings. 
Sentence2: Glass or fiberglass buildings are used to protect plants by keeping them warm.

glass