Letters that used to be sounds
Hundreds of years ago, knight sounded much more like its spelling. There was a k sound before the n, and the gh stood for a breathy sound, a bit like the ch in the Scottish word loch. The same k sound began knee and know, and a g sound began gnat and gnaw.
Then, little by little, people stopped saying them. The breathy gh sound had gone from standard English by about 1600, and the k before n had faded away by about 1750. The w in write and the b at the end of lamb went quiet too, though their dates are harder to pin down.
Why the spelling did not change too
Printing arrived in England in 1476. Over the next 150 years or so, printed spelling slowly became more regular, just as the way people spoke was changing a great deal. So the spellings settled on older ways of saying words, and many of them still show how English sounded over 500 years ago.
Myth: William Caxton's printing press fixed English spelling in one go.
What the evidence says: It happened slowly. Caxton's own spelling varied from page to page, and printed spelling only settled into something close to today's in the middle of the 1600s.
Letters that were never sounds
Some silent letters were never said in English at all. Debt and doubt came into English from French as dette and doute, with no b. Scholars who knew the Latin words behind them, such as debitum, slipped a b in to show the family link. That happened gradually, from about 1400 to 1600. The spelling stuck, but the sound never arrived.
Receipt was once spelt receite, until a p was added to match Latin. Writers tried the same p in conceit and deceit, but it only stuck in receipt.
Island is odder still. In Old English it was igland, with no s at all. In the 1500s writers added one because they linked it with isle, a different word that came from French. The two words have nothing in common but their meaning.
Myth: Every silent letter was once pronounced.
What the evidence says: Many were, but not all. The b in debt and doubt, the p in receipt and the s in island were added by writers and were never part of how English speakers said those words.
Shakespeare made a joke of it. In Love's Labour's Lost, a show-off schoolmaster called Holofernes grumbles about people who say “det” when they “should pronounce ‘debt’ — d, e, b, t”. The joke is on him: nobody said the b.
Sometimes an added letter did end up being said. Perfect was once parfit. After writers gave it a Latin-looking c, people slowly began to pronounce the c too.
| Silent letter | Examples | Was it ever said? |
|---|---|---|
| k before n | knight, knee, know | Yes, until about 1750 |
| g before n | gnat, gnaw | Yes |
| w before r | write, wrong | Yes |
| gh | night, light | Yes, until about 1600 |
| b after m | lamb | Yes |
| b after m | limb, numb | No: added in writing to match words like lamb |
| gh | delight | No: added once gh had gone silent in other words |
| b | debt, doubt | No: added to look like Latin |
| p | receipt | No: added to look like Latin |
| s | island | No: copied from isle |
Letters that came with borrowed words
English speakers don't usually say the p in words from Greek like pneumonia, though French and German speakers do. The p in psychology is silent in English too.
What silent letters do today
Some of them do a useful job: they keep word families looking alike when the words sound different. You can't hear the g in sign, but you can in signature. And the w in two links it to twin, twice and twenty, which all have to do with two.
That doesn't make English spelling tidy: most linguists doubt the old claim that it is close to ideal. Many silent letters are simply history, a record of how English used to sound or of what writers once thought it should look like.
Questions people ask
Why is the k in knight silent?
Because people stopped saying it. The k was sounded hundreds of years ago and had faded from standard English by about 1750, but by then the spelling had settled.
Was the b in debt ever pronounced?
No. Scholars added it to match the Latin word debitum, and English speakers never said it.
Do children learn about silent letters at school?
In England, yes. The national curriculum's spelling appendix lists words beginning kn, gn and wr in Year 2, and words with silent letters, such as doubt, island, lamb and knight, in Years 5 and 6.