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.

Example Input: Sentence1: Polyps usually reproduce asexually. 
Sentence2: Polyps usually reproduce several different ways.
Example Output: Polyps

Example Input: Sentence1: Without light there is no sense of vision. 
Sentence2: Glass causes a sense of vision.
Example Output: sense

Example Input: Sentence1: Pollution is the release of harmful substances into the environment. 
Sentence2: treating water is used to remove pollution before drinking.
Example Output:
Pollution