Q From Steve Waclo: Wandered to your wonderful site while looking for the derivation of the word heat, as it applies to racing terminology (as in ‘the third heat’).
A We’re so familiar with the use of heat in that way that few people ever stop, as you have done, to wonder where it comes from. I didn’t know either, and had to look it up.
It seems, from the historical record laid out in the big Oxford English Dictionary (without which few such questions could ever reach a resolution), that it is a special application of the word heat that refers to the result of physical exertion.
From the fourteenth century on, it could be applied to a single burst of intense physical activity of any sort, often in the phrase at a heat, at one go, in one continuous operation (as late as 1855, John Lothrop Motley wrote in his book The Rise of the Dutch Republic: “On one occasion he hanged twenty heretics, including a minister, at a single heat”). By the seventeenth century, it was used specifically for what we would now call a warm-up, especially a brief canter by a horse just before a race: the diarist John Evelyn used it that way in 1670: “The jockeys breathing their fine barbs and racers, and giving them their heats”.
It seems that the two ideas came together so that heat started to refer to a horse race, particularly to one episode of a larger contest. The first examples we know about date from the middle of the seventeenth century. In 1676, for example, the London Gazette announced that “The second Plate will be Run for on the same Moor, by three Heats”.
Later the meaning was extended to refer to a single part of many types of contest. In broadening the sense, and with the passage of time, a direct mental link to the heat of exertion has been lost.