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: accomodation 
Words: elevation, level, round, flat, townhome
Example Output: elevation

Example Input: Category: physical property 
Words: bulky, angular momentum, pasty, fat, big
Example Output: big

Example Input: Category: type of rigidity 
Words: united, firm, unbending, rough, solid
Example Output:
united