Measurement technology

The fourteenth entry is o intervalo de calibração, and the first noun has a wall standing inside it. Intervallum was nothing abstract in Latin. Vallum was the rampart of a camp, the line of stakes driven into the earth, and the intervallum was the strip of open ground between two of them, the empty lane a soldier could walk down. Everything the word does today came out of that gap: the distance between two marks on a scale, the silence between two notes, and here the stretch of time a certificate is allowed to cover before the instrument goes back to the laboratory. What makes it worth a minute is that English happens to hold both ends of the family. « Interval » arrived from intervallum by way of French, keeping the abstraction and leaving the stakes behind. « Wall » is that same vallum, borrowed far earlier and straight into Old English, while the Romans were still putting them up across the north. So the garden wall and the calibration interval are one word landing twice, several centuries apart, and only one of the two still has anything to do with defending anything.