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: All cells share some of the same structures and basic functions. 
Sentence2: Inside the cell is a structure called the nucleus.
Example Output: cells

Example Input: Sentence1: All sharks are predators. 
Sentence2: hiding can be used for avoiding sharks.
Example Output: sharks

Example Input: Sentence1: Algae Algae Green algae are the simplest of green plants. 
Sentence2: Chloroplasts are organelles that are found in the cells of the simplest of green plants.
Example Output:
green