Dal د

Dal is the eighth letter of the modern Arabic order and the fourth of the older abjad order, from which it takes the numeral value four. It is one of the smallest letters in the script, a short angular hook that sits on the line and takes up little more room than a dot. It carries no pointing of its own, and the same hook marked with a single dot above is dhal, one of the six letters Arabic added to the alphabet it inherited.

Dal belongs to the group of six letters that join only to the right. A connected group of Arabic writing therefore ends whenever a dal is reached, and the next letter starts a fresh group. Six letters out of twenty-eight behave this way, and because several of them are among the commonest in the language, the effect on the look of a written line is considerable: Arabic words are not single unbroken chains but sequences of connected clusters separated by narrow gaps. Learners often read those gaps as word breaks, which they are not.

Dal is a sun letter, so the lam of the definite article assimilates to it in speech and is not heard, although it is still written. Its name descends from the Northwest Semitic daleth, whose sense was door, and the letter is the direct cognate of Hebrew dalet, Syriac dalath and the corresponding Samaritan letter. The Arabic name preserves the form of the older word and none of its meaning.

Arabic is a cursive script in which letters within a word are normally joined, and it is one of the few scripts in the world for which cursive writing is not a style but the ordinary and only form. Print, handwriting and inscription all connect the letters. There is no equivalent of the roman distinction between separated capitals and joined script.

Six letters break that rule. Alif, dal, dhal, ra, zay and waw connect to the letter before them but not to the letter after, so each one closes the connected group it stands in. The next letter must begin a new group in its initial or isolated form. This is why a single Arabic word may appear on the page as two, three or four separate clusters, and why counting clusters is no guide to counting words.

The behaviour is inherited rather than designed. The Nabataean cursive from which Arabic descends had already begun to link some letters and not others, and Arabic fixed the pattern that had emerged. Its consequences run through the script. Because the six non-joiners produce a natural gap, calligraphers use them to control the density and rhythm of a line, and the classical hands have rules about how far a preceding letter may be stretched to reach one. Typesetting and, later, digital text encoding had to model the same behaviour: rendering an Arabic string means choosing among the isolated, initial, medial and final form of each letter according to its neighbours, which is why an alphabet chart of isolated forms represents the letters accurately and represents Arabic writing hardly at all.