Al-

Al- (Arabic: ال‎‎, also transliterated as el- as pronounced in varieties of Arabic) is the definite article in the Arabic language: a particle (ḥarf) whose function is to render the noun on which it is prefixed definite. For example, the word كتاب kitāb "book" can be made definite by prefixing it with al-, resulting in الكتاب al-kitāb "the book". Consequently, al- is typically translated as in English.

Unlike most other particles in Arabic, al- is always prefixed to another word and it never stands alone. Consequently, most dictionaries will not list it as a separate word, and it is almost invariably ignored in collation. Similarly, al- is not a permanent component of the word to which it is prefixed. It is added and removed to toggle between the definiteness and indefiniteness of the word.

As a particle, al- does not inflect for gender, plurality, or grammatical case. The sound of the final -l consonant, however, can vary; when followed by a sun letter such as t, d, r, s, n and a few others, it is replaced by the sound of the initial consonant of the following noun, thus doubling it. For example: for "the Nile", one does not say al-Nīl, but an-Nīl. When followed by a moon letter, like m-, no replacement occurs, as in al-masjid ("the mosque"). This affects only the pronunciation and not the spelling of the article.

To put al- into perspective, there are many ways in which Arabic words can be made definite. These include the use of personal pronouns like "me", the use of proper nouns like "Saudi Arabia", demonstrative pronouns like "this man", relative pronouns like "the man who ...", vocation like "O man", possession like "my man", and of course the definite article like "the man". Apart from possession, prefixing a noun with al- is the weakest form of definiteness. That is, saying "the man" does not define the man being referred to as clearly as saying "this man", for example.

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