Instructions: 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: Viruses are not cells at all, so they are neither prokaryotes nor eukaryotes. 
Sentence2: Influenza viruses are classified as orthomyxoviruses.
Output:
Viruses