Arabic has no separate word for ‘a’ or ‘an’ as in ‘a chair’ or ‘a apple’, so these words are indefinite
nouns
al is added to a noun to make it definite. This is the case for both masculine and feminine nouns. Fore example waladun (a boy) and al-waladu (the boy) (refer to case note below for different ending).
sun and moon letters
The sun letters cause the pronumciation of the al to change. The l is assimilated and instead the initial letter of the noun is pronounced twice (written with a shadda). For e.g. As-sayyaratu ((refer to case note below for different ending).
- The sun letters are:
- ta, tha, dal, dhal, ra, za, sin, shin, sad, dad, ta, za, lam, nun
- The moon letters are the remainder of the letters
elision
If al comes directly after a vowel, the a of the al will drop (or elide), leaving the l. This only affects the pronunciation and not the spelling. For e.g. - al-bayt (the house) and fi l-baytu (in the house). - al-mumarridatun and hiya l-mumarridatu (refer to case note)
case note
When a noun is made definite the neutral ( nominative) case ending above the final letter becomes a dhamma.