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: Human papillomavirus vaccine is aimed at the cause of most cases of cervical cancer. 
Sentence2: A vaccine against a virus can protect against cervical cancer.

vaccine