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: Nitrogen is found in proteins, nucleic acids, and chlorophyll. 
Sentence2: Lawns eat nitrogen.
Example Output: Nitrogen

Example Input: Sentence1: Ozone depletion results in higher levels of UV radiation reaching Earth. 
Sentence2: less ozone means more ultraviolet light.
Example Output: Ozone

Example Input: Sentence1: DNA contains genetic instructions for proteins, and RNA helps assemble the proteins. 
Sentence2: dna is required for life.
Example Output:
DNA