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: 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: a light bulb is used for seeing in the dark. 
Sentence2: light is required for seeing.
Example Output: seeing

Example Input: Sentence1: Behind the warm front are thick, low stratus clouds and possibly more rain. 
Sentence2: cloudy and rainy weather is accompanied by stratus clouds.
Example Output:
clouds