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.

Ex Input:
Sentence1: intense heat has a negative impact on an organism. 
Sentence2: intense heat has a negative impact on plants.

Ex Output:
heat


Ex Input:
Sentence1: if an object in a fluid is more dense than that fluid then that object will sink in that fluid because of gravity. 
Sentence2: Most seeds are more dense than water.

Ex Output:
dense


Ex Input:
Sentence1: Ribosomes are structures in the cytoplasm where proteins are made. 
Sentence2: For example, insulin is a protein hormone.

Ex Output:

proteins