Given a category and a set of five words, find the word from the set that does not belong (i.e. is the least relevant) with the other words in the category. Words are separated by commas.
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Question: Category: type of sandwich 
Words: open-faced, hero, club, discothek, hamburger

Answer: discothek


Question: Category: consumer product 
Words: merchandise, happy, thing, content, service

Answer: happy


Question: Category: personal characteristic 
Words: scorching, cool, ethical, unruffled, confident

Answer:
scorching