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

Ex Output:
coyote


Ex Input:
Sentence1: Ovulation is the release of an egg from an ovary. 
Sentence2: The release of an egg during ovulation is used in reproduction.

Ex Output:
Ovulation


Ex Input:
Sentence1: Life changes, life evolves. 
Sentence2: Cynodonts became more mammal like as they continued to change.

Ex Output:

changes