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: social gathering 
Words: club, bar, dance hall, discothek, roll
roll

Category: aesthetic characteristic 
Words: fair, size, medium, dishonest, level
dishonest

Category: temperature 
Words: chill, unflappalbe, tropical, icy, cool

unflappalbe