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: Mating is generally preceded by courtship. 
Sentence2: Mating is generally similar across species.
Example Output: Mating

Example Input: Sentence1: boiling is when liquids are heated above their boiling point. 
Sentence2: If the pressure is reduced, the boiling point is lowered.
Example Output: boiling

Example Input: Sentence1: Filter feeders supply food to predators 8. 
Sentence2: sponges supply food to predators.
Example Output:
food