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: friction causes the temperature of an object to increase. 
Sentence2: When we increase the temperature of objects, they always expand.
Example Output: increase

Example Input: Sentence1: Cultivation is easier if soil is loose. 
Sentence2: soil with more oxygen is easier to cultivate.
Example Output: Cultivation

Example Input: Sentence1: Electricity flows when a battery is connected to an object like a watch, toy, or flashlight. 
Sentence2: Flashlights are powered by batteries to produce light.
Example Output:
battery