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: window material 
Words: panel, translucent fabric, spatula, metal, glass
Example Output: spatula

Example Input: Category: measurement unit 
Words: meter, inch, foot, heel, pound
Example Output: heel

Example Input: Category: bird 
Words: parrot, sandpiper, crane, hoist, heron
Example Output:
hoist