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: If there is no movement friction is zero. 
Sentence2: Movement causes the temperature of an object to increase.
movement

Sentence1: Competition may lead to aggressive behaviors or displays of aggression. 
Sentence2: Aggression Aggression and violence often go together.
aggression

Sentence1: Caecilians can be found in moist soil near rivers and streams in tropical regions. 
Sentence2: Earthworm-like amphibians live in soil near rivers in tropical regions.

regions