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: Instead, the body is covered with a protective shell of bony armor. 
Sentence2: Most mollusks have protective of bony armor.
Example Output: armor

Example Input: Sentence1: Cultivation is easier if soil is loose. 
Sentence2: soil with more oxygen is easier to cultivate.
Example Output: Cultivation

Example Input: Sentence1: predicting weather requires studying weater. 
Sentence2: meteorologists require studying weater.
Example Output:
requires