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: Mitosis is cell division. 
Sentence2: mitosis often causes growth.
Example Output: Mitosis

Example Input: Sentence1: Producers use energy and inorganic molecules to make food. 
Sentence2: Green plants use energy and inorganic molecules to make food.
Example Output: energy

Example Input: Sentence1: Shallow tropical waters are remarkable places. 
Sentence2: corals form large colonies in remarkable places.
Example Output:
places