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: elements 
Words: water, heat, fire, empower, cool
empower

Category: physical property 
Words: protein, pasty, fat, thin, angular momentum
protein

Category: store status 
Words: close, not open, nearest, busy, finished for the day

nearest