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.

Sentence1: keeping food cold is used for keeping food fresh. 
Sentence2: Keeping food cold is used to keep food simple and natural as possible.
cold

Sentence1: Mammalian teeth are important for digestion. 
Sentence2: bats' teeth are important for digestion.
digestion

Sentence1: Mammals breathe with the help of a diaphragm. 
Sentence2: Hiccups are a result of spasms of the diaphragm.

diaphragm