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: Dromaeosaurs are part of the theropod group of dinosaurs. 
Sentence2: Birds evolved from a group of bipedal dinosaurs that included Dromaeosaurs.
Example Output: Dromaeosaurs

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: Animals may compete for territory, water, food, or mates. 
Sentence2: Animals such as lions and tigers fight.
Example Output:
Animals