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: Nausea and vomiting are caused by activation of the vomiting center in the brain. 
Sentence2: the brain is responsible for removing toxic material from the stomach.

brain