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.

Example Input: Sentence1: when a body of water receives more water than it can hold , a flood occurs. 
Sentence2: Floods are deadly, floods are devastating.
Example Output: flood

Example Input: Sentence1: Mammals that are viviparous are called therian mammals. 
Sentence2: Mouse-sized viviparous mammals evolved by Jurassic times.
Example Output: Mammals

Example Input: Sentence1: Animals may compete for territory, water, food, or mates. 
Sentence2: Larger animals dominate in competition for food, mating partners, and nesting space.
Example Output:
food