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: Eggs are usually laid in a nest. 
Sentence2: birds have nests.
Example Output: nest

Example Input: Sentence1: if an organism becomes too hot then that organism may die. 
Sentence2: a plant can collapse if it gets too hot.
Example Output: hot

Example Input: Sentence1: Kidney failure may be treated with dialysis. 
Sentence2: kidney failure may be treated with a procedure to filter the blood.
Example Output:
Kidney