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: acceptable, fine, comfortable, pretty, well

A: pretty
****
Q: descending, disgusted, emotionalities, emotional supports, down

A: descending
****
Q: unyielding, synergy, sustainability, united, firm

A:
unyielding
****