Research Summary The study addresses one of the important topics in semantics, which is minor derivation, represented here by the justification of naming.Among them: I disagreed with Ibn Sidah in all the explanations he rejected for the naming of things, as their validity was established in their respective sections, except for his rejection of the explanation for the naming of Tayy (that they were the first to cover the watering places), his rejection of the explanation for the naming of the bird of prey (that it sings at night), and his rejection of the explanation for the naming of the bird of prey (that it sings at night), referring to birds of prey because they hide in the earth.The nature of the study necessitated that the research be structured into an introduction, a preface, and three main sections: the first addresses the justifications for naming that Ibn Sidah rejected concerning the thing itself; the second addresses the justifications for naming that Ibn Sidah rejected concerning the relationship of the thing to something else; and the third addresses the justifications for naming that Ibn Sidah rejected concerning morphological forms.Among them: The criteria Ibn Sidah established for rejecting the explanations for naming things include, in general, contradiction of reality, incorrect derivation of the name, and transmission from an unreliable source.c) Verifying information from linguists and consulting their works to avoid attributing to them what they did not write, as Ibn Sidah did by attributing to Ibn Duraid the derivation of 'bardhun' (meaning a man's gait) from the verb 'bardhan' (meaning to become heavy).Linguists have been concerned with studying the justification of naming, and among the most prominent of the ancient linguists who studied it was Ibn Sidah (d. 458 AH) in his dictionary Al-Muhkam and Al-Muhit Al-A'zam.Keywords: Ibn Sidah - Explanations - Naming - Definitive - Descriptive - Analytical.