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: physical activity 
Words: stoop, crouch, bow, duck, dog
dog

Category: computers 
Words: errands, file, download, text, folder
errands

Category: employment activity 
Words: ice, sack, let go, remove, fire

ice