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: Energy enters ecosystems in the form of sunlight or chemical compounds. 
Sentence2: Energy enters ecosystems in the form of photons.
Example Output: Energy

Example Input: Sentence1: information in an organism 's chromosomes cause genetic traits to be passed down to that organism 's offspring. 
Sentence2: information in Man's chromosomes cause genetic traits to be passed down to offspring.
Example Output: chromosomes

Example Input: Sentence1: Protozoa make humans sick when they become human parasites. 
Sentence2: Species of Sarcocystis can parasitize humans and make them sick.
Example Output:
human