The Five Nouns: abū, akhū, dhū

Five Arabic nouns show their case in writing with a long vowel whenever they are the first term of an idafa or take a pronoun suffix. This lesson practises أب (father), أخ (brother), حم (father-in-law) and ذو (owner of, having):

• nominative ends in و: هذا أبو محمد, أخوها, ذو أهمية
• accusative ends in ا: رأيت أبا محمد, رأيت أخاه, بيتا ذا حديقة
• genitive ends in ي: مع أبي الطالب, على أبيك, مع رجل ذي خبرة

ذو always stands before a noun and takes the case of the word it describes; its feminine ذات (امرأة ذات خبرة) does not show case in writing. With ي (my) the forms stay أبي and أخي in every case, and outside idafa these are ordinary nouns (أب, الأخ). Names such as أبو أحمد (Abu Ahmad) are the same construction.