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: Antibodies are large, Y-shaped proteins that recognize and bind to antigens. 
Sentence2: Some of the antibodies, antophospholipid antibodies, cause blood clots.
Example Output: Antibodies

Example Input: Sentence1: Plants exhibit phototropism, or growing toward a light source. 
Sentence2: Phototropism means growing toward the energy of light.
Example Output: phototropism

Example Input: Sentence1: Small Intestine Structurally, the small intestine is a tubular organ. 
Sentence2: Absorption of nutrients occurs mainly in a tubular organ.
Example Output:
organ