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 property 
Words: obese, heavy, area, chunky, fat

Answer: heavy


Question: Category: moral characteristic 
Words: milky, fair, ok, loyal, unprejudiced

Answer: milky


Question: Category: mode of transportation 
Words: train, fly, fish, soar, bus

Answer:
fish