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: Sperm pass out of the body through the urethra. 
Sentence2: Sperm travel from the testicles through the vas deferens to the seminal vesicles and the prostate.
Example Output: Sperm

Example Input: Sentence1: Results can be damaging or disastrous. 
Sentence2: Lack of immunization can be damaging or disastrous.
Example Output: damaging

Example Input: Sentence1: Most genes contain the instructions for a single protein. 
Sentence2: Most genes contain the instructions for protein destinations.
Example Output:
Most

