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: window material 
Words: glass, coating, panel, spatula, lead
spatula

Category: consumer product 
Words: merchandise, happy, thing, content, service
happy

Category: emotional status 
Words: decent, alert, content, dull, fine

dull