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: Common fossils include plant fossils like ferns.
Example Output: plant

Example Input: Sentence1: If there is enough moisture in the clouds, rain is produced. 
Sentence2: Clouds lacking water reduces rainfall.
Example Output: clouds

Example Input: Sentence1: Sweat wets the skin, and when it evaporates, it cools the body. 
Sentence2: Normally, the body cools itself by sweating.
Example Output:
Sweat