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 requires time.
Example Output: healing

Example Input: Sentence1: mineral graphite is used for making pencil lead. 
Sentence2: Diamond and graphite are made of carbon.
Example Output: graphite

Example Input: Sentence1: Some animals attract mates with scent. 
Sentence2: animal courtship can involve scent.
Example Output:
animals