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: the digestive system breaks food into nutrients for the body. 
Sentence2: Meat is a nutrient-dense food.
Example Output: food

Example Input: Sentence1: killing microorganisms in food can be used to extend the shelf life of that food. 
Sentence2: Cooking can be used to extend the shelf life of food.
Example Output: be

Example Input: Sentence1: Most protists have motility. 
Sentence2: Motility is lost if the specimen dries.
Example Output:
motility