Given a set of five words, generate the word from the set that does not belong (i.e. is the least relevant) with the other words. Words are separated by commas.

[Q]: hot, optimist, cool, calm, relaxed
[A]: hot


[Q]: folder, hardware, file, firewall, support
[A]: support


[Q]: joyful, fearful, content, happy, books
[A]:
books