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: All lizards are reptiles. 
Sentence2: Lizards are tetrapod vertebrates that produce amniotic eggs.
Example Output: lizards

Example Input: Sentence1: Aquatic animals are adapted to living within certain salinity ranges. 
Sentence2: Animals adapted to living within certain salinity ranges require great amounts of water to survive.
Example Output: adapted

Example Input: Sentence1: Lymph is a fluid that leaks out of capillaries into spaces between cells. 
Sentence2: Lymph is a liquid that leaks out of capillaries into spaces between cells.
Example Output:
Lymph