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: tumble, summer, fall, bend, lift

Answer: summer


Question: Category: aesthetic characteristic 
Words: fair, unprejudiced, level, tone, milky

Answer: unprejudiced


Question: Category: mode of transportation 
Words: car, swim, walk, train, fly

Answer:
swim