The head or chief brake operator on a train, or the front part of a braking system.
Compound of 'brake' and 'head' (from Old English 'heafod'). Railway terminology from the 19th-20th centuries.
On freight trains, the 'brakehead' was second in command only to the conductor—they had to know every inch of the train and understand braking physics intuitively!
Complete word intelligence in one call. Free tier — 50 lookups/day.