Al –Kawthar is the Surah with the ordinal number of 108 in the Quran and only has 3 short verses but in include a word that has baffled Islamic scholars for a long time and they never knew what it meant. In Arabic: سورة الكوثر
This Surah is known as a Meccan Surah, but some believe that it may be Medinan. Some others have said that this Surah might have been revealed twice; once in Mecca and once in Medina, but the narrations cited on the occasion of its revelation attest to the first idea which says it is Meccan.
So what do Muslim Scholars say about this unknown word “Al –Kawthar”
Al-Bukhaari narrated in his Saheeh from Anas that the Prophet said: “Whilst I was walking in Paradise, I saw a river whose banks were domes of hollow pearls.” I said, “What is this, O Jibreel?” He said: “This is al-Kawthar which your Lord has given to you.” The angel struck it with his hand and its mud or its perfume was of the most fragrant (or pure) musk.
According to another report narrated in al-Musnad (12827) also from Anas, the Prophet was asked about al-Kawthar and he said: “That is a river which Allaah has given to me, in Paradise. It is whiter than milk and sweeter than honey, and in it are birds whose necks are like the necks of camels.” ‘Umar said: “Those are soft birds.” The Messenger of Allaah said: “Eating them is even softer, O ‘Umar.” Classed as saheeh by al-Albaani in Saheeh al-Targheeb wa’l-Tarheeb, 3740.
This make sense right? Not really because this word don’t follow any of the Arabic grammatical rules in forming word from the three letter verb stem in the past tense.
As a general rule: any word that you can find its stem ( 3 letter verb in the past tense) is an Arabic word, if not then it has a foreign origin.
So what do other scholars say?
Narrated Ibn ‘Abbas: The word 'Al-Kauthar' means the abundant good which Allah gave to him (the Prophet Muhammad). Abu Bishr said: I said to Sa'id ibn Jubayr, "Some people claim that it (Al-Kauthar) is a river in Paradise." Said replied, "The River that is in Paradise is one item of that good which Allah has bestowed upon him (Muhammad)."
Narrated Abu ʿUbaidah : I asked 'Aisha 'regarding the verse:--'Verily we have granted you the Kauthar.' She replied, "The Kauthar is a river which has been given to your Prophet on the banks of which there are (tents of) hollow pearls and its utensils are as numberless as the stars."
Narrated Haritha bin Wahb: I heard the Prophet mentioning the Lake-Fount (Al-Kauthar), saying, "(The width of the Lake-Fount) is equal to the distance between Medina and Sana' (capital of Yemen)." Haritha said that he heard the Prophet saying that his Lake-Fount would be as large as the distance between Sana' and Medina. Al-Mustaurid said to Haritha, "Didn't you hear him talking about the vessels?" He said, "No." Al-Mustaurid said, "The vessels are seen in it as (numberless as) the stars."
To avoid making this very long and boring there are many theories that don’t agree with each other’s which simply means that no one’s really knows.
“Kauthar” does not means the abundant because there is no name driven in this form in the Arabic language and the “Kawthar” looks similar to the word “abundant” but that is all.
And since Islamic scholars assumed that the Quran is 100% Arabic and there is not even a single foreign word in it, even though old Islamic scholars say there are a lot, the Islamic world end up with a dead road in finding the meaning of this word.
So we have to look in another direction
After searching for a long time I found it in the answer. In the Ancient Canaanite language there are two words that sound exactly like Kawthar: Kotharat and Kothar the first is the female variation of the second and both of them are names of Ancient Canaanite gods:
So how does this fit in?
Simple: let us read the chapter that is named Al- Kawthar:
Muhammad was mocked for not having children so these verses promised him of a great reward which is children. Kauthar means fertility and it is the name of the goddess of fertility in Ancient Canaanite, let us not forget that the Quran has many Canaanite words in it.
In a matter of fact most of the religious terms in the Quran has Ancient Canaanite roots:
Spirit, Angels, etc