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: emotional status 
Words: downward, unhappy, down, shameful, disgusted
downward

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

Category: corporate 
Words: unyielding, firm, llc, alignment, private

unyielding