Cacadu is derived from the Khoikhoi word tkakadao and the 'c's in the name are pronounced with a click. The click is made by placing the tongue directly behind the teeth and retracting the tongue into the mouth rapidly. In English culture the same sound is made when showing ones disappointment about an event and is often written as 'tisk, tisk'. The same clicking sound is used in isiXhosa.
The Khoikhoi were the first known inhabitants of the area that is today known as the Cacadu District Municipality.
Strictly speaking, there is no official or scholarly translation of the word Cacadu. One interpretation of the Cacadu is that it means 'river with bulrushes' and the particular river given this name is thought to be Papenkuils River, which enters Algoa Bay between the Port Elizabeth suburbs of Deal Party and North End. Another interpretation is translated to a "landscape of semi-arid plains, undulating mountains and the sea".
What is generally accepted is that the 'Ca' in Cacadu means 'place of' which is common to many of the Nguni languages (hence Kwa Zulu meaning place of the Zulu) and hence place of bulrushes makes more sense. Other examples of Khoikhoi words from the reghion include Karoo - place of thirst; Kadou (now spelt and pronounced Addo) - place of the river crossing or drift; Kouga (also spelt and pronounced Coega) - place of the hippo; Kabega - place of reeds.