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: the number of rings in a tree trunk can be used to estimate the age of the tree. 
Sentence2: Dendrochronologist: A person who studies tree ring growth.

rings