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: emotional status 
Words: kind, down, sad, backward, emotionalities
backward

Category: construction 
Words: winch, steam roller, egret, derrick, crane

egret