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: Roundworms make up the phylum Nematoda. 
Sentence2: Also, nematoda and rotifera are important groups contributing to soils.
Example Output: Nematoda

Example Input: Sentence1: Insect wings are attached to the dorsal side of their thorax. 
Sentence2: wings are attached to the dorsal side of the insect.
Example Output: dorsal

Example Input: Sentence1: Macroevolution is more than repeated rounds of microevolution. 
Sentence2: evolution over geologic time above the level of the species is more than repeated rounds of microevolution.
Example Output:
microevolution