Arabic/LearnRW/al- Assimilation

The definite article of Arabic is الـ (Alif-Laam), known asلام التارف (Laam al-Ta3reef).

The first letter of the Laam al-Ta3reef is a Hamzat-Wasl (همزة وصل), an alif with a 9aad (ص) written above it (ٱ). We do not write the ص on the alif in writing (we simply know it is there, as no words in Arabic begin with alif (only alif with hamza (أ). A Hamzat-Wasl takes the sound of a vowel immediately before it, if there is one; if not, it makes the same sound as fatha at the beginning of the word (أَ).

An example of the Hamzat-Wasl taking the sound of a preceding vowel is الأُممُ الـمُتَّحِدة (Al-Umamu l-Muttahida), "The United Nations".

The spelling of Laam al-Ta3reef is with 3ain and not alif: لام التعريف. Here it means 'the'. But in some places it means 'all'. Then it is known as Laam al-Jins, where jins means the whole category. E.g., al-7amdu = 'all praise' (الحمد).