high ball: a signal to a train engineer to go ahead

Also spelled highball, this signal was originally semaphored by the raising of a ball at the side of the tracks. Later, the conductor or brakeman would wave a lantern in a high arc to signal "full speed ahead." The term was also used figuratively to mean a clear road ahead, as in "We had a highball trail into town." Used as a verb, it meant to move very quickly, not necessarily on a train. A 1961 American Speech article quotes, "Imagine yourself on the seat of an enormous freighter, high-balling it down a West Coast highway."

Around the end of the nineteenth century, high ball began to be used as a name for a drink consisting of alcohol and a mixer, such as whiskey and soda. Whether the two meanings are connected is unclear. Were high balls the signal for a party to move full speed ahead? Sophisticates continued to drink high balls until the early sixties, when it became more common to order drinks by their components - "scotch and water" or "gin and tonic."