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: Genetics is the study of inheritance. 
Sentence2: Pedigrees are useful tools for studying genetics.
Example Output: Genetics

Example Input: Sentence1: Streams may start with runoff or water seeping out of a spring. 
Sentence2: Most water comes from precipitation.
Example Output: water

Example Input: Sentence1: pasteurization reduces the amount of bacteria in milk. 
Sentence2: Bacteria and blue-green bacteria are prokaryotic cells.
Example Output:
bacteria