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Related to tuning machine: machine heads
A mechanism in the head of a guitar or similar instrument, consisting of a worm screw and gear attached to a post around which a string is wound, used to adjust the tension and regulate the pitch of the string. Also called tuning head.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.