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: adding salt to a solid decreases the freezing point of that solid. 
Sentence2: Water density decreases with temperature and increases with salt content.
Example Output: decreases

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

Example Input: Sentence1: Many plants respond to the days growing shorter in the fall by going dormant. 
Sentence2: Plants can be divided at any time, although the dormant or rest period is best.
Example Output:
dormant