The word ال the

The word ال is an article which means the. When the article ال is used before a word the tanwin at the end of the word must be changed to its definite form i.e. without its tanwin, as shown below:

1. بَيْتٌ baitun a house: اَلْبَيْتُ al-baitu the house
2. حَجَرٌ hajarun a rock: اَلْحَجَرُ al-hajaru the rock
3.  إِمَامٌ imaamun an imam: اَلْإِمَامُ al-imaamu the imam
4. مُدَرِّسٌ mudarrisun a teacher: اَلْمُدِرِّسُ al-mudarrisu the teacher
5. حَاْسُوْبٌ haasuubun a computer: اَلْحَاْسُوْبُ al-haasuubu the computer