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: Here, the lungs supply the blood with oxygen. 
Sentence2: Brain cells die quickly if their blood supply is cut off.
Example Output: blood

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: Head hair is especially important in preventing heat loss from the body. 
Sentence2: Alopecia Hair loss is referred to as alopecia.
Example Output:
hair

