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: Translation reads the genetic code in mRNA and makes a protein. 
Sentence2: Nucleotide sequences are read in mRNA and a protein is made.
Example Output: mRNA

Example Input: Sentence1: Plants exhibit phototropism, or growing toward a light source. 
Sentence2: Phototropism means growing toward the energy of light.
Example Output: phototropism

Example Input: Sentence1: Small animals are harmed by pesticides. 
Sentence2: Protecting plants can sometimes come at the expense of harming small animals.
Example Output:
Small