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: After a seed is planted it is watered. 
Sentence2: seeds need water.
Example Output: seed

Example Input: Sentence1: if humans disturb animals in a location then those animals will move to a different location. 
Sentence2: The human being is self-aware.
Example Output: humans

Example Input: Sentence1: Collar cells have tiny hairs that trap the particles. 
Sentence2: Particles A particle is simply a very tiny piece of matter.
Example Output:
particles