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: Capillaries are microscopic vessels. 
Sentence2: Lymph is a fluid that leaks out of microscopic vessels into spaces between cells.
Example Output: microscopic

Example Input: Sentence1: Earthquakes cause massive damage. 
Sentence2: tectonic plates being pushed together causes massive damage.
Example Output: damage

Example Input: Sentence1: using a gasoline engine requires burning gasoline. 
Sentence2: using a gasoline engine requires consuming gasoline.
Example Output:
engine