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: Crops are plants that are grown for food or other uses. 
Sentence2: insects destroy plants.
Example Output: plants

Example Input: Sentence1: a plant requires sunlight to grow. 
Sentence2: Grass needs air and sunlight.
Example Output: sunlight

Example Input: Sentence1: Coffee is an excellent source of caffeine. 
Sentence2: Coffee stimulates the central nervous system.
Example Output:
Coffee