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: employment activity 
Words: recruit, replace, sack, heat, fire

Answer: heat


Question: Category: animal 
Words: walk, flap, fish, fly, bats

Answer: flap


Question: Category: aesthetic characteristic 
Words: level, fair, milky, decent, ghostly

Answer:
decent