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: cold fronts cause thunderstorms as they pass by. 
Sentence2: Thunderstorms create havoc.
Example Output: thunderstorms

Example Input: Sentence1: All photos are digital images. 
Sentence2: satellites are used to take photos from space.
Example Output: photos

Example Input: Sentence1: Largest of the oceans on Earth is the Pacific Ocean . 
Sentence2: the gravitational pull of the Moon on the Pacific causes the tides.
Example Output:
Pacific