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: a pulley is used for lifting objects. 
Sentence2: Resistance exercises are weight-lifting exercises.
Example Output: lifting

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: an animal requires nutrients to grow and heal. 
Sentence2: An animal requires ingestion to grow and heal.
Example Output:
grow