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: trustworthy, variety, tone, ghostly, fair

Answer: trustworthy


Question: Category: physical property 
Words: brittleness, protein, bulky, skinny, fat

Answer: protein


Question: Category: boats 
Words: dock, head, rudder, deck, call

Answer:
call