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 viruses live in a dormant state inside the body. 
Sentence2: a virus can live in the brain.
Example Output: viruses

Example Input: Sentence1: hiding can be used for avoiding predators. 
Sentence2: Camouflage is used for avoiding predators.
Example Output: avoiding

Example Input: Sentence1: Metals are extremely versatile materials. 
Sentence2: If an object is made of metal then that objects has the properties of the metal.
Example Output:
Metals