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: walk, flap, fish, fly, bats
flap

Category: emotional status 
Words: sad, remorseful, down, ashamed, sliding
sliding

Category: moral characteristic 
Words: size, dishonest, unjust, well, fair

size