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: intense heat has a negative impact on an organism. 
Sentence2: intense heat has a negative impact on plants.
Example Output: heat

Example Input: Sentence1: Absorption of nutrients occurs mainly in the small intestine. 
Sentence2: The small intestine is the main place where food absorption occurs.
Example Output: intestine

Example Input: Sentence1: smoking causes direct damage to the lungs. 
Sentence2: Tar causes damage to the lungs.
Example Output:
damage