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: Faster metabolism means more calories consumed, and usually, weight loss. 
Sentence2: mammals generate heat by consuming calories.
Example Output: calories

Example Input: Sentence1: Producers make food from inorganic molecules. 
Sentence2: Decomposition is the breakdown of organic molecules into inorganic molecules.
Example Output: inorganic

Example Input: Sentence1: Invertebrates are animals that lack a vertebral column, or backbone. 
Sentence2: Fish are backboned aquatic animals.
Example Output:
backbone