Definition: 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.
Input: Sentence1: Mammals can also generate little bursts of heat by shivering. 
Sentence2: Intense shivering and severe pain are natural body reflexes to cold water.

shivering