In Arabic there are two types of words:

  1. مْنْصَرِف – words that follow the normal pattern
    (indefinite=tanween, state of raf’=dhamma, state of nasb=fatha, state of jarr=kasra)
  2. غَير منصرف – words that break the normal pattern
    (never takes tanween, state of jarr=fatha)

Going back to the names, عُمْر is pronounced ‘Umar, and عَمْرو is pronounced ‘Amr.

What you probably recognized by now is that the letter و is not pronounced. So the question remains, why is it there? The reason it is there is to avoid confusion between ‘Amr and ‘Umar. If the و was dropped, one would not be able to tell the difference between the two since the majority of texts do not include vowels. So it is only meant as a place marker. This is important so that one does not mix up ‘Umar ibn al-Khattab and ‘Amr ibn al-‘As when reading historical texts.

Now that you understand this, let’s discuss some details.

 

The name عُمَر is غَير منصرف. This means that it has 2 special rules.
1. It nevers takes tanween
2. In the state of jarr (when it comes after a preposition or is a mudaf ilaih), it will take a fatha.

Let’s look at some examples:
جَاءَ عُمَرُ – Umar came
ضَرَبَ زَيْدٌ عُمَرَ – Zaid hit ‘Umar
مَرَرْتُ بِعُمَرَ – I passed by ‘Umar

 

The name عمرو is مْنْصَرِف meaning that it follows the normal pattern of words. However, it is important to remember one fundamental: the only reason the و is present is to differentiate itself from عمر. Thus, if one is able to differentiate between the two without a و then the و will disappear.

Let’s look at some examples:
جَاءَ عَمْرُو – ‘Amr came
مَرَرْتُ عَمْرٍو – I passed by ‘Amr
ضَرَبَ زَيْدٌ عَمْرًا – Zaid hit ‘Amr.
(In this case the و dropped because an alif was needed – that is for another post – and since عمر cannot take an alif we know it must be ‘Amr.)