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: Carbon dioxide is controlled by the carbon cycle. 
Sentence2: Carbon dioxide is controled by the carbon circle and is transferred between organisms and atmosphere.
Example Output: controlled

Example Input: Sentence1: Lancelet larvae are free-swimming. 
Sentence2: some larvae lack a hardened backbone.
Example Output: larvae

Example Input: Sentence1: Bikes and tricycles are also decorated. 
Sentence2: pushing on the pedals of a tricycle causes it to move.
Example Output:
tricycles