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: baby animals 
Words: lust, kitten, deer, bambi, fawn
lust

Category: bird 
Words: winch, swift, crane, hoist, ostrich
winch

Category: physical activity 
Words: jump, exercise, fall, spring, roll

spring