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.

Category: window material
Words: glass, spyhole, handle, coating, knive
knive

Category: secretary duty
Words: file, errands, type, folder, order office supplies
folder

Category: aesthetic characteristic
Words: detailed, attractive, custody, pretty, fine
custody