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 fossils of a water animal or plant are found in a place then that place used to be covered by water in the past. 
Sentence2: Fossils are the remains of prehistoric life.
Example Output: fossils

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: Abundant waters call for stories of travel and trade, and protecting ships from dangers. 
Sentence2: Ships are used for travel and trade.
Example Output:
trade