headstockPronunciation: /ˈhɛdstɒk/Definition of headstock noun 1a set of bearings in a machine, supporting a revolving part. 2the widened piece at the end of the neck of a guitar, to which the tuning pegs are fixed. 3the horizontal end member of the underframe of a railway vehicle. headstock in other Oxford dictionaries Definition of headstock in the US English dictionary