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.

Example Input: Category: aesthetic characteristic 
Words: fair, unprejudiced, level, tone, milky
Example Output: unprejudiced

Example Input: Category: physical property 
Words: fat, area, ugly, capacitance, calcium
Example Output: calcium

Example Input: Category: emotional status 
Words: kind, down, melancholy, opposite of up, unhappy
Example Output:
opposite of up