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: Extinct animals include the dodo bird and the saber-toothed tiger. 
Sentence2: The last dodo birds could not produce offspring.

dodo