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: Whale sharks are viviparous , giving birth to live young. 
Sentence2: Therian mammals give birth to live young, called live birth.

birth