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.

Q: Category: boats 
Words: hull, deck, rudder, check, lifeline

A: check
****
Q: Category: ocean 
Words: late, wave, blue, current, drink

A: late
****
Q: Category: temperature 
Words: cool, calm, refreshing, mild, tropical

A:
calm
****