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

Example Input: Category: bird 
Words: crane, concrete pourer, goose, hoist, duck
Example Output: concrete pourer

Example Input: Category: physical property 
Words: ugly, protein, large, heavy, fat
Example Output:
protein