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.

Ex Input:
Sentence1: Animals can communicate with sounds, chemicals, or visual cues. 
Sentence2: cats can communicate with sounds, chemicals or visual cues.

Ex Output:
chemicals


Ex Input:
Sentence1: moss causes chemical weathering. 
Sentence2: Sphagnum moss mixed with peat moss.

Ex Output:
moss


Ex Input:
Sentence1: Ethanol, a form of alcohol, is already the most common biofuel. 
Sentence2: a form of alcohol is used to produce electricity by burning.

Ex Output:

alcohol