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: emotional status 
Words: down, emotional state, loveful, ashamed, flat
Example Output: flat

Example Input: Category: emotional status 
Words: truss rod, emotional supports, emotional upsets, emotionalities, fret
Example Output: truss rod

Example Input: Category: bird 
Words: derrick, crane, heron, hummingbird, excavator
Example Output:
excavator