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: when a river floods , that river deposits soil in flood plains. 
Sentence2: when a river floods, it deposits soil in generally marshy areas.
Example Output: deposits

Example Input: Sentence1: ultraviolet light causes sunburn. 
Sentence2: Sunburn risk is higher at elevation.
Example Output: sunburn

Example Input: Sentence1: dew is formed when water vapor condenses over night. 
Sentence2: If there is a greater dew point there is more water vapor.
Example Output:
vapor