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: angry, joyful, tools, fearful, content

A: tools
****
Q: ecstatic, specialty, substance, content, merchandise

A: ecstatic
****
Q: headstock, string, sad, fret, strap lock

A:
sad
****