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: igneous rocks are formed from magma cooling. 
Sentence2: magma solidifies into igneous rocks.
Example Output: magma

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: Petals attract pollinators to the flower. 
Sentence2: Hummingbirds are the most common bird pollinators.
Example Output:
pollinators