As-salamu 'alaykum waRahmatullahi waBarakatuHu.
"Is every single word in the Qur'aan originally from the Arabic language?"
Shaykh Ismail Kamdar (hafizahullah) explains this topic as follows:
[...] Actually, this is something the scholars of the past debated on. Different teachers follow different opinions on this issue.
In Yasir Qadhi's "An introduction to the sciences of the Qur'an" he explains both opinions with their evidences:
However, is every single word in the Qur'aan originally from the Arabic language? In other words, does the Qur'aan use words from other languages? There exist narrations from some of the Companions, and many grammarians after them, concerning certain words in the Qur'aan which were claimed to be of non-Arabic origin. Thus, for example, Ibn Abbaas claimed that the word toor was Syriac for mountain, tafiqa meant "to intend' in the Roman language, hudnaa was Hebrew for repentance, sijl was Persian for book, sundus meant a soft cloth in Hindi (probably referring to Sanskrit), miskhaat was a shining lamp in an Ethiopian language, and sirri was Greek for a small river. His student 'Ikrimah was also of the same opinion.
This opinion led some later scholars to come forth with numerous examples of words that were claimed to be non-Arabic in origin, yet mentioned in the Qur'aan. As-Suyotee (d. 911 A.H.) compiled a list of over a hundred words in the Qur'aan that were claimed to be non-Arabic in origin, and even versified these words in a poem."
Other scholars, however, denied the claim that there could be any non-Arabic words in the Qur'aan. Basing their evidences on the Qur'aanic verses quoted above, they held the view that these verses precluded the existence of foreign words in the Qur'aan. Imaam ash-Shaafi'ee (d. 204 A.H.) was particularly strict in this matter, for he wrote concerning some grammarians of his time, "And some have spoken in this topic (of foreign words in the Qur'aan), and had they restrained themselves from speaking it would have been better, anil safer tor them! For some ol them have presumed that the Qur'aan is part Arabic and part foreign! Yet the Qur'aan is explicit that there is nothing in the Book of Allah except that it is in the language of the Arabs..."
In attempting to refute the opinion that the Qur'aan contains foreign words, at-Tabaree (d. 310 A.H.) claimed that these particular words were used by both of these languages simultaneously, and thus the Companions' claims that these words were non-Arabic only meant that they were also used by other languages as well. However, this is not a satisfactory explanation, as the word must have originated in one of the two languages.
Aboo 'Ubayd al-Qaasim ibn Sallaam (d. 224 A.H.) explained the above narrations from Ibn 'Abbaas correctly when he said,
The correct opinion with me is that both of the above opinions (meaning that there are foreign words in the Qur'aan, and that the Qur'aan is only in Arabic) arc correct. This is because the origin of these words is foreign, like the scholars said (referring to the narrations of Ibn 'Abbaas). However, these words entered into the Arabic language, and were transformed to Arabic words, and the foreign letters were exchanged for Arabic ones, until they became a part of Arabic. Then the Qur'aan was revealed, and by this time these words had mixed in with the Arabic language. Therefore, he who says that the Qur'an is only in Arabic is correct, and he who says that there are some foreign words is also correct.'"
In other words, these particular phrases are originally non-Arabic in origin. However, as is the case with any language, these words were 'borrowed' by Arabic, and were used so commonly that they became a part of the Arabic language. Thus, for all practical purposes, these words became 'a part of fluent Arabic, and were used in poetry... and if an Arab were ignorant of these words, it was as if he were ignorant of other Arabic words.'
Therefore, the correct opinion is that there are no non-Arabic words in the Qur'aan, although there are words that have non-Arabic origins. Due to the continued usage of these words by the Arabs, however, they can no longer be considered foreign.
An Introduction to the Sciences of the Qur'an, pp. 26-27
Allah knows best
