Sun and Moon Letters - Rule

Rule

When followed by a sun letter, the l of the Arabic definite article al- assimilates to the initial consonant of the following noun, resulting in a doubled consonant. For example, for "the Nile", one does not say al-Nīl, but an-Nīl. When the definite article is followed by a moon letter, no assimilation takes place.

Sun letters represent all coronal consonants except ج ǧīm (see below). Since the article al- ends in a coronal consonant, it lends itself to assimilation with these sounds.

The sun and moon letters are as follows:

Sun letters
t d r z s š l n
Moon letters ء ه
ʾ b ǧ ʿ ġ f q k m w y h

Read more about this topic:  Sun And Moon Letters

Famous quotes containing the word rule:

    This at least should be a rule through the letter-writing world: that no angry letter be posted till four-and-twenty hours will have elapsed since it was written.
    Anthony Trollope (1815–1882)

    The only rule is, do what you really, impulsively, wish to do. But always act on your own responsibility, sincerely. And have the courage of your own strong emotion.
    —D.H. (David Herbert)

    Every writing career starts as a personal quest for sainthood, for self-betterment. Sooner or later, and as a rule quite soon, a man discovers that his pen accomplishes a lot more than his soul.
    Joseph Brodsky (b. 1940)