Read this column to the end and win instant cashback! That’s right! Just scan the words to qualify for this amazing cashback deal!

Only joking. The fact is, I’m no longer sure what “cashback” means. I can still remember the first time I presented my Switch card at the supermarket checkout and was asked: “Would you like cashback?” How’s that again? Would I like my cash back? Is the Pope a catholic?

Having established that, yes, I would very much like my cash back please, the only question remaining was:“How much?” That’s a tough one. How about giving all of it back?

At this point the penny dropped. I wasn’t being offered cash back. I was being offered cash. What’s more, it was my own cash. Quite some deal, yes?

These days, I don’t give this particular transaction a second thought. For supermarket cashback, simply read “readies”. But outside those big revolving doors,“cashback” seems to have acquired a baffling variety of meanings, from commission to discount to loyalty points to sweetener.

Here’s a letter out of the blue, offering me a new credit card. “Earn cashback award on every purchase you make,” it says. “The more you use your card, the more you can earn!” At every turn, somebody’s waving cashback in my face. Failing that, they’ll slip it to a school or hospital or dogs’ home of my choice. I’d be mad not to go for a cashback mortgage. Even a program that shuts down my computer when it’s not in use is called a CashBack Screensaver because it saves electricity.

And then there are the car deals.

Let me get this straight. If I buy a car for pound;8,000, they will send me a cheque for pound;250. So why don’t they just sell the car for pound;7,750?

“Psychology,” says a friend who understands these things. “Also, it disguises the discount and makes it impossible to compare interest rates or prices, as well as being a tax dodge, a way round the Consumer Credit Act and a device for tricking customers into borrowing more money.”

“A bit like butchers adding water to ham?” I venture.

My friend looks puzzled.“Er, no,” he says. “Not like that at all.”

By chance, I have stumbled on the one thing that cannot be described as cashback. How’s that for progress?