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: tide, belated, signal, current, jetstream

A: belated
****
Q: hot, optimist, cool, calm, relaxed

A: hot
****
Q: tough, rough, resistant, firm, combined

A:
combined
****