In Arabic and Maltese, all consonants are classified into two distinct groups known as sun letters ( , ) and moon letters (Arabic: , ).

This distinction affects the way the definite article (equivalent to "the" in English) is assimilated or pronounced before consonants: when a word begins with a sun letter, the definite article assimilates with the initial consonant of the word.

The names stem from how the definite article interacts with the nouns "Sun" and "Moon" in Arabic (and Maltese). In Arabic, al-shams (“the Sun”) becomes ash-shams (assimilating the lām), while al-qamar (“the Moon”) remains unchanged. Similarly, in Maltese, "the Sun" is ix-xemx (with assimilation), while "the Moon" is il-qamar (without assimilation).

Rule

When followed by a sun letter, the of the Arabic definite article assimilates to the initial consonant of the following noun, resulting in a doubled consonant. For example, "the Nile" is pronounced , not .

When the Arabic definite article () is followed by a moon letter, no assimilation takes place.

The sun letters represent the coronal consonants according to the phonology of Classical Arabic, and the moon letters represent all others. Note that the mnemonic (pronounced somewhat like aibgh hajak wakhaf eaqimah) groups all moon letters.

The sun and moon letters are as follows:

Jīm

The letter is pronounced differently depending on the region of the speaker. In many regions it represents a coronal consonant such as or . However, in Classical Arabic, it represented a palatalized voiced velar plosive or a voiced palatal plosive . A contemporary pronunciation as is retained in Egypt, Oman, and coastal Yemen or in eastern hinterland Yemen, and as a variant in Sudan. As a result, it was classified as a moon letter, and it does not assimilate the article in Classical Arabic. Maltese ġ is also considered a moon consonant, whereas its voiceless counterpart ċ is a sun consonant.

However, in some varieties of Moroccan, Mesopotamian, and Palestinian Arabic, (often //) assimilates, like a sun letter, e.g., 'camel'.

Emphatic consonants

In Arabic dialects, like Palestinian, al before an emphatic consonant only assimilates in place of articulation but not in pharyngealization, hence instead of ( 'table').

Maltese

The sun (konsonanti xemxin) and moon (konsonanti qamrin) letters are as follows:ir-raġel ra r-raġel" (that man saw the man). When a word starts with two consonants, the definite article used is l-, but an i is attached at the beginning of the word: skola > l-iskola and Żvezja > l-Iżvezja.

The sound (represented by the letters and ) function in the same way regardless of if it is a sun or moon letter, e.g. (the meat) is il-laħam in Maltese and al-laḥm in Arabic or (the game) is il-logħba in Maltese and al-luʿba in Arabic.

Orthography

In the written language, the ⟨⟩ is retained regardless of how it is pronounced. When full diacritics are used, assimilation may be expressed by putting a arALAshaddah ⟨ ّ⟩ on the consonant after the ⟨⟩. Non-assimilation may be expressed by placing a arALAsukūn over the ⟨⟩.

Most modern-written Arabic names (including personal names and geographical Arabic names) do not follow the consonant assimilation rule or the shaddah when Latinized in Latin-spelled languages. Sometimes the sun and moon rules are not followed in casual speech. They are also mostly spaced rather than hyphenated.

E.g. personal name:

• - Al Rahman or El Rahman instead of Ar-Raḥmān

transliterated geographical name:

• - Al Jumhuriyah Al Tunisiyah instead of al-Jumhūrīyatu t-Tūnisīyah

See also

• Arabic phonology

• Arabic grammar

References