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: Streams may start with runoff or water seeping out of a spring. 
Sentence2: streams may start with runoff or h2o seeping out of a spring.
Example Output: Streams

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: Nuts are also consumed by deer, turkey, foxes, wood ducks and squirrels. 
Sentence2: wood ducks can feed at more than one trophic level.
Example Output:
ducks