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.

Category: boats 
Words: head, hull, knockout, deck, dock
knockout

Category: temperature 
Words: cold, hot, cool, popular, relaxing
popular

Category: food 
Words: wiener, entree, frank, meat, brash

brash