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: Most mammals have hair, or fur, covering their body. 
Sentence2: Most mammals have a body covering for keeping warm.
Example Output: body

Example Input: Sentence1: riding a bike does not cause pollution. 
Sentence2: riding a bike does not release particles.
Example Output: bike

Example Input: Sentence1: Another part of the inner ear is used for balance. 
Sentence2: The inner ear helps with sensing and maintaining body position.
Example Output:
ear