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

Example Input: Sentence1: Petals attract pollinators to the flower. 
Sentence2: Something a daisy has attracts pollinators.
Example Output: attract

Example Input: Sentence1: a thermometer is used to measure temperature. 
Sentence2: Fever is measured using a thermometer.
Example Output:
measure