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: construction 
Words: hoist, tackle, digger, excavator, crane
tackle

Category: physical property 
Words: fat, vitamin c, area, brittleness, absorption
vitamin c

Category: kitchenware 
Words: knive, glass, colander, bowl, metal

metal