According to rhetoric scholars, eloquent speech depends on the eloquence of words and sentences, and "strangeness" stands as an obstacle. There are words in the Holy Qur'an that did not have a clear meaning for the people of Hijaz in the revelation era, and they are called "Gharib al-Qur'an". Through a descriptive-analytical approach and relying on library sources, the present article aims to re-examine the definition of rhetoric (balagha) by focusing on reviewing the requirement of fluency in rhetoric and considering the strange words of the Qur'an. Balagha scholars have divided strange words into good and wild and considered only wild ones to be a hindrance to fluency. They are into this idea that the strange words that are good does not contradict the eloquence of the word. The time-bound, location-bound and domain-bound strangeness are the three branches of good strangeness. According to the author’s opinion, a speech is considered eloquent only and if only it complies with and is appropriate to the current requirements. These requirements are generally followed by fluency; however, fluency is not always a condition of eloquence; sometimes the situation requires the use of strange words. In these cases, using the word “fluent” disrupts the eloquence of the speech. In this view, the eloquence of words has only one criterion, and that is to match the current requirements, and the fluency of words and statements is not a condition within this criterion.