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: police punishment 
Words: ticket, comfortable, prime, custody, fine
comfortable

Category: elements 
Words: ban, fire, combustion, ground, flame
ban

Category: emotional status 
Words: fine, wispy, alert, calm, relaxed

wispy