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.
--------
Question: Category: boats 
Words: head, hull, knockout, deck, dock

Answer: knockout


Question: Category: boxing terminology 
Words: deck, ring, head, knockout, glove

Answer: head


Question: Category: direction 
Words: down, flat, downward, miserable, descending

Answer:
miserable