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.

Sentence1: Every living thing, animal and plant, are given a classification. 
Sentence2: Cells make up the structure and function of plants and animals.
animal