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: condensing causes a liquid to form. 
Sentence2: Air carries moisture that causes a liquid to form.
Example Output: causes

Example Input: Sentence1: a tape measure is used to measure length. 
Sentence2: Length The Base unit for length in the metric system is the meter .
Example Output: length

Example Input: Sentence1: electrocution causes harm to an organism. 
Sentence2: Electrocution causes organisms to be pained.
Example Output:
causes