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: Absorption of nutrients occurs mainly in the small intestine. 
Sentence2: The small intestine is the main place where food absorption occurs.
Example Output: intestine

Example Input: Sentence1: waxy leaves are used for storing water by some plants. 
Sentence2: waxy leaves are used for water conservation by some plants.
Example Output: leaves

Example Input: Sentence1: Tectonic plates can contain both continental and oceanic crust F 25. 
Sentence2: Crust being pushed together causes earthquakes.
Example Output:
crust