Each of the small pegs on the head of a guitar, used for tightening the strings.
More example sentences
- From then onwards all tuning takes place down at the bridge using the fine tuners (I've not used the regular machine heads yet - the guitar just stays in tune).
- They do not necessarily need to be in tune - the machine heads on the modern bass are basically only there for effect - nails will serve just as well.
- He'd carefully scrubbed the machine heads and pick-ups with the detachable head of a burnt-out electric toothbrush, and wiped the sweat and dust from each string until they gleamed packet-fresh.