A WORD, PLEASE — average

continuity: Next, Professor Aubrey Vellum, with a word that has survived a very bad storm.

the verdict: You know the moment when a test comes back, and somebody asks how the whole class did? Your teacher does a quick sum on the board, announces the class average, and everybody quietly decides whether to feel smug or sorry.

a word, please: Average. A word, please.

the crack: Here's the secret: that word wasn't born anywhere near a classroom. It was born at sea, on the merchant ships of the medieval Mediterranean, in the worst moment a sailor could face. A storm hits, the ship starts to go under, and the crew heaves cargo over the side, barrels and bales and somebody's precious silk, just to keep her afloat. When the battered ship limped into port, someone had to pay for what went into the waves. So the law said every merchant whose goods survived chipped in a fair, proportional share. The Italians called that shared loss avaria , and the French called it avarie. Both most likely come from an Arabic word, awariya , meaning 'damaged goods.' Scholars once argued it might be Latin instead, but today the Arabic story wins.

the collision: English picked it up in the late fourteen hundreds and gave it an ending like damage and salvage, so it sounded right at home on the docks. Then, in the seventeen hundreds, mathematicians spotted the clever part, adding everything up and splitting it evenly. They kept that idea and quietly left the shipwreck behind. By the eighteen hundreds, average could simply mean ordinary. People sometimes guess it went the other way round, with ordinary first and the maths later. It's a tidy guess, and it's backwards, and the real story is better. The word we now use to win arguments about whether this summer was hotter than normal began as the bill after a storm.

the glimmer: And that tells you something lovely about us. Long before it meant ordinary, an average was how people promised that nobody would face the loss alone.

the exit: That's the word. So if anyone calls you average today, take it as a compliment. You're the sort who helps pay for the storm.