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: Light is the visible form of electromagnetic energy. 
Sentence2: Electromagnetic energy enters the eye through an opening called the pupil.
Example Output: electromagnetic

Example Input: Sentence1: Infection is what ultimately leads to death. 
Sentence2: scraping oneself on a contaminated object may cause death.
Example Output: death

Example Input: Sentence1: the looseness of soil has a positive impact on a plant 's roots' growth in that soil. 
Sentence2: Root growth and development are extremely important to plant growth.
Example Output:
roots'