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: sprint, cow, duck, jog, squat
cow

Category: weather 
Words: impartial, 70, warm, fair, luke
impartial

Category: outdoor sport activity 
Words: whale, fish, swim, kayak, hike

whale