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: Interest in fossils is worldwide. 
Sentence2: paleontologists study something with worldwide interest.
Example Output: Interest

Example Input: Sentence1: if an organism becomes too hot then that organism may die. 
Sentence2: if an organism overheats then that organism may die.
Example Output: die

Example Input: Sentence1: Gene cloning is the process of isolating and making copies of a gene. 
Sentence2: Gene cloning results in an allele.
Example Output:
cloning