TASK 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.
PROBLEM: Sentence1: Endospores are commonly found in soil and water. 
Sentence2: Dirt is really misplaced soil.

SOLUTION: soil

PROBLEM: Sentence1: a polar bear requires a cold environment. 
Sentence2: polar bears live where there are fewer animals.

SOLUTION: bear

PROBLEM: Sentence1: Aggression is behavior that is intended to cause harm or pain. 
Sentence2: Aggression is behavior that is intended to cause hurt.

SOLUTION:
Aggression