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: Blood type is important for medical reasons. 
Sentence2: Type O is important for medical reasons.
Example Output: important

Example Input: Sentence1: First, the bottle is calibrated with a graduated cylinder. 
Sentence2: calibration is performed with a cylinder.
Example Output: calibrated

Example Input: Sentence1: the force of water against the seed coat causes a root to emerge from a seed. 
Sentence2: The force of water helps a root sprout.
Example Output:
force