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: physical activity 
Words: summer, roll, plummet, fall, exercise

Answer: summer


Question: Category: window material 
Words: metal, handle, dish, glass, vinyl

Answer: dish


Question: Category: emotional status 
Words: miserable, down, melancholy, disgusted, ground

Answer:
ground