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: dew is formed when water vapor condenses over night. 
Sentence2: When water vapor condenses overnight, the temperature has reached the dew point.
Example Output: condenses

Example Input: Sentence1: looking at bright objects has a negative impact on the eyes. 
Sentence2: Looking at bright objects have a negative impact on the retina.
Example Output: bright

Example Input: Sentence1: if soil is permeable then water easily flows through that soil. 
Sentence2: The suitability for septic drainfields is poor because of slow permeability.
Example Output:
permeable