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.

Q: Sentence1: Any antigen that causes an allergy is called an allergen. 
Sentence2: Antigens are proteins foreign to the body.

A: antigen
****
Q: Sentence1: skin is used for protecting the body from harmful substances. 
Sentence2: Acids are harmful to tissue.

A: harmful
****
Q: Sentence1: electrocution causes harm to an organism. 
Sentence2: Electrical shock Electric shock is caused by current passing through the human body.

A:
electrocution
****