If you look up the word ‘Zulu’ in the dictionary, it can refer to a variety of things: it can be a reference to the Zulu people (amaZulu); to the language spoken by the Zulus (isiZulu); or, completely arbitrarily, it can refer to the letter ‘Z’, as used in the international phonetic alphabet (i.e. Whiskey, X-ray, Yankee, Zulu)!
More romantically people often talk about how the name describes the heavens or the sky, with the amaZulu being ‘the people of heaven’ and KwaZulu, ‘the place of heaven’. Supposedly this stems from the fact that the origin, or etymology, of the word ‘zulu’ can be traced back to ’emaZulwini’, which translates to ‘the heavens’. But according to certain oral histories, the name comes from the founding ancestor of the Zulu royal line, which came about in around 1670.* Before the reign of King Shaka, the term ‘Zulu’ referred only to the specific clan that recognised Zulu as its founding ancestor. But after the Mfecane wars, which saw Shaka’s assimilation of land and people, the term came to refer to those subsumed under the Zulu Kingdom. There is much debate around the extent of the Mfecane and the Zulu kingdom. See more HERE.
History and politics have effects on the present. Today the isiZulu is the most spoken language in South Africa. According to the 2011 census nearly 12 million people in South Africa speak the language.
* As per www.sahistory.org.za