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: nutritional value 
Words: iron, heavy, vitamin c, fat, brittleness
Example Output: brittleness

Example Input: Category: shady activities 
Words: falsehood, banned, heavy, unlicensed, fudge
Example Output: heavy

Example Input: Category: direction 
Words: down, forward, unhappy, ground, falling
Example Output:
unhappy