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: Some herbivores have more than one stomach. 
Sentence2: Camels are an herbivore.
Example Output: herbivores

Example Input: Sentence1: Viruses are parasites of cells. 
Sentence2: Populations of viruses do not grow through division because they are parasites.
Example Output: are

Example Input: Sentence1: Fish have a circulatory system with a two-chambered heart. 
Sentence2: Trout is an extremely versatile fish.
Example Output:
Fish