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: Mitosis is cell division. 
Sentence2: mitosis often causes growth.
Example Output: Mitosis

Example Input: Sentence1: a flower 's purpose is to produce seeds. 
Sentence2: Every job has meaning and purpose.
Example Output: purpose

Example Input: Sentence1: bees convert nectar into honey. 
Sentence2: Older workers search for nectar and make the enzymes necessary to convert it to honey.
Example Output:
honey