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: weathering means breaking down rocks from larger whole into smaller pieces by weather. 
Sentence2: Trash collectors work in all types of weather, including rain and snow.

Ex Output:
weather


Ex Input:
Sentence1: Passive immunity lasts only as long as the antibodies survive in body fluids. 
Sentence2: A pregnant woman will pass antibodies to the fetus.

Ex Output:
antibodies


Ex Input:
Sentence1: Birds have a large brain relative to the size of their body. 
Sentence2: Creatures with feathers and wings have a large brain relative to the size of their body.

Ex Output:

body