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: Osteoporosis is a disease characterized by a decrease in bone mineral density. 
Sentence2: a disease in which osteoclasts are more active than osteoblasts results in a decrease in bone mineral density.
Example Output: bone

Example Input: Sentence1: Autumn brings the changing of the seasons. 
Sentence2: Earth 's tilt on its rotating axis causes autumn.
Example Output: Autumn

Example Input: Sentence1: Magnetism A compass works on the principle of magnetism and points to the North Magnetic Pole. 
Sentence2: A compass works on the principle of the objects ability repel each other.
Example Output:
compass