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: Sponges are filter feeders. 
Sentence2: Hawksbills feed primarily on filter feeders.
Example Output: feeders

Example Input: Sentence1: Leeches are external parasites. 
Sentence2: Leeches live on the surface of their hosts.
Example Output: Leeches

Example Input: Sentence1: Ribosomes are small organelles where proteins are made. 
Sentence2: Bacteria lack ribosomes.
Example Output:
Ribosomes