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: wind is used for producing electricity. 
Sentence2: Wind is caused because of pressure differences in the atmosphere.
Example Output: wind

Example Input: Sentence1: Mammalian predators include the coyote and bobcat. 
Sentence2: a coyote's teeth is important for digestion.
Example Output: coyote

Example Input: Sentence1: Most carcinogens cause cancer by producing mutations in DNA. 
Sentence2: most carcinogens cause cancer by producing mutations in deoxyribonucleic acid.
Example Output:
cancer