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: animal 
Words: pounce, fly, swim, walk, walk
walk

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

Category: outdoor sport activity 
Words: wrestle, bat, canoe, fish, hunt

bat