D is for Delta

Alphabetic Origins

I always thought that the letter D, coming from the Greek delta, Δ, was originally the pictogram of a door. Around 800 BC the Greeks adopted the shape and name from the Phoenician word for ‘door’, dalet, in modern Hebrew delet. While the triangular shape of the Greek letter may make one think of a tent entrance, the similarity is fortuitous: dalet derives from a Semitic verbal root meaning ‘swing’, suggesting a hinged door or panel.

From Phoenician dalet came the Greek word meaning a wooden panel or tablet, deltos, and its diminutive deltion meaning a small writing-panel on which a stylus might be used to scratch letters (‘deltiology’ means the study of postcards). Hundreds of wooden postcards like this one have been found in the Roman fort of Vindolanda in Northumberland:

In fact the original letter shape is said to have been derived from the Egyptian hieroglyph for ‘door’:

Although the hieroglyph looks like a shallow bathtub, it represents a chunky door lying on its side, perhaps one deepened by recesses such as this one found in Saqqara:

The hieroglyph seems to have inspired the angular - and triangular - shape that we find in the Phoenician alphabet around 1000 BC:

However, as long ago as 1904 it was suggested by the orientalist Theodor Nöldeke that the Phoenician shape, tail and all, was originally meant to represent a fish, dig in that language, which would provide the acrophonic d. Fish such as the European flounder were after all a key food source for the maritime Phoenicians.

If so, how did a letter meaning ‘fish’ came to be called ‘door’? One theory is that since another kind of fish (perhaps an eel) had been adopted for a different alphabetic letter, nun, to avoid confusion the Phoenicians eventually replaced dig with the name for door, dalet. But the triangular shape remained, and with the name dalet attached the letter was adopted by the Greeks and characteristically geometrised to make Δ.

The Greek letter-shape, inverted as ∇, gives rise to our use of the term for (e.g.) the Nile delta:

The Etruscans wrote the letter with a curved side around 600 BC, and from them the Romans adopted the letter as our D.

The letter’s tortuous history shows that the door to the secrets of alphabetic development is not always wide open. We are sometimes apt to flounder, and might even need to dig down into murky depths of fishy speculation.