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.

Ex Input:
Sentence1: Pregnancy is the carrying of one or more offspring from fertilization until birth. 
Sentence2: An elephant carries their offspring from fertilization until birth, 22 months later.

Ex Output:
fertilization


Ex Input:
Sentence1: Sweat glands produce more sweat. 
Sentence2: When the body is hot, something coming from a gland is produced to cool the body.

Ex Output:
glands


Ex Input:
Sentence1: an animal requires nutrients for survival. 
Sentence2: Proper digestion is vital for nutrient absorption.

Ex Output:

nutrients