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 body of water receives more water than it can hold , a flood occurs. 
Sentence2: Floods are deadly, floods are devastating.
Example Output: flood

Example Input: Sentence1: Refrigerators are major users of electricity. 
Sentence2: Keeping food fresh for a long period of time requires a lot of electricity.
Example Output: electricity

Example Input: Sentence1: Sexual reproduction combines an egg and a sperm. 
Sentence2: combining an egg and sperm increases genetic diversity.
Example Output:
combines