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: aesthetic characteristic 
Words: medium, just, light, ghostly, fair
just

Category: elements 
Words: fire, retire, ice, air, earth
retire

Category: boxing terminology 
Words: gunwale, box, jab, corner, deck

gunwale