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: type of sandwich 
Words: club, roll, doorstep, discothek, toast
discothek

Category: emotional status 
Words: worried, angry, jack, fret, emotional upsets
jack

Category: aesthetic characteristic 
Words: fine, attractive, dull, there, firstrate

firstrate