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: healing requires rest. 
Sentence2: Healing and cell regeneration follows.
Example Output: healing

Example Input: Sentence1: Most fungi get organic compounds from dead organisms. 
Sentence2: Moulds, yeasts, rusts, smuts, mildews, and mushrooms are all types of fungi.
Example Output: fungi

Example Input: Sentence1: Dilation occurs when cell walls relax. 
Sentence2: Dilation is often uncomfortable.
Example Output:
Dilation