Index-linked describes pay, a pension, a benefit, or sometimes a price that goes up or down as a published index of prices goes up or down. The “index” here is not the list at the back of a book. It is a number that tracks how expensive ordinary things have become — often a consumer price index. If your pension is index-linked, it is meant to keep its buying power when shops get dearer: when that index climbs, the payment is supposed to climb with it (some schemes can also fall if prices fall, though many pensions only go up). The phrase is especially British; American English more often says inflation-linked or talks about a cost-of-living adjustment. Banks also sell “index-linked” products tied to a stock-market index — a later stretch of the same idea (tied to some published number) — but the older everyday use about wages and pensions is about prices in the shops.