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: aesthetic characteristic 
Words: well, milky, variety, tone, fair

Answer: well


Question: Category: moral characteristic 
Words: just, make the grade, well, unjust, fair

Answer: make the grade


Question: Category: aesthetic characteristic 
Words: fine, exquisite, bright, dull, prison

Answer:
prison