Sun and moon letters
distinction between two groups of Arabic consonants
In Arabic and Maltese, all consonants are classified into two distinct groups known as sun letters (Arabic: حروف شمسية ḥurūf shamsiyyah, Maltese: konsonanti xemxin) and moon letters (Arabic: حروف قمرية ḥurūf qamariyyah, Maltese: konsonanti qamrin).
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 /l/ of the Arabic definite article al- assimilates to the initial consonant of the following noun, resulting in a doubled consonant. For example, "the Nile" is pronounced an-Nīl, not al-Nīl.
When the Arabic definite article (الْـ) 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 اِبْغِ حَجَّكَ وَخَفْ عَقِيمَهُ (pronounced somewhat like aibgh hajak wakhaf eaqimah) groups all moon letters.
“Sun and moon letters” enters the record as distinction between two groups of Arabic consonants. Crown Archives preserves that source wording while asking what moon, letters and distinction can confirm, complicate or overturn.
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“Sun and moon letters” is worth following because a concise public description often conceals a longer documentary argument. Here, moon, letters and distinction provides the most credible route into that argument.
The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Aug 20, 2026. The linked authority identifier is Q1124683. None of the 0 selected statements returned an explicit reference.
The absence of detail may reflect summary conventions rather than a lack of surviving documentation. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
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This entry incorporates text from “Sun and moon letters” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.