Hadza is a language isolate spoken along the shores of Lake Eyasi in Tanzania by around 1,000 Hadza people, who include in their number the last full-time hunter-gatherers in Africa. It is one of only three languages in East Africa with click consonants. Despite the small number of speakers, language use is vigorous, with most children learning it, but UNESCO categorizes the language as vulnerable.

The Hadza go by several names in the literature. Hadza itself means "human being." Hazabee is the plural, and Hazaphii means "they are men." Hatza and Hatsa are older German spellings. The language is sometimes distinguished as Hazane, "of the Hadza".^{[citation needed]}

Tindiga is from Swahili watindiga "people of the marsh grass" (from the large spring in Mangola) and kitindiga (their language). Kindiga is apparently a form of the same from one of the local Bantu languages, presumably Isanzu.^{[citation needed]} Kangeju (pronounced Kangeyu) is an obsolete German name of unclear origin. Wahi (pronounced Vahi) is the German spelling of the Sukuma name for either the Hadza west of the lake, or perhaps a Sukuma clan that traces its ancestry to the Hadza.^{[citation needed]}

Hadza is a language isolate. It was once classified by many linguists as a Khoisan language, along with its neighbour Sandawe, primarily because they both have click consonants. However, Hadza has very few proposed cognates with either Sandawe or the other putative Khoisan languages, and many of the ones that have been proposed appear doubtful. The links with Sandawe, for example, are Cushitic loan words, whereas the links with southern Africa are so few and so short (usually single consonant–vowel syllables) that they are most likely coincidental. A few words link it with Oropom, which may itself be spurious; the numerals itchâme /it͡ʃʰaame/ "one" and piye /pie/ "two" suggest a connection with Kwʼadza, an extinct language of hunter-gatherers who may have had recently shifted to Cushitic. (Higher numerals were borrowed in both languages.)^{[citation needed]}

Several parallels have been collected with many of the Afroasiatic languages. A lexicostatistical proposal for Hadza as a member of the family, perhaps particularly close to Chadic, was criticized by specialists of Hadza and Cushitic as more likely consisting of several layers of loanwords and some chance resemblances, due to insufficient regularity in sound correspondences and a lack of grammatical evidence for a relationship. George Starostin finds the hypothesis of a relationship of Hadza with Afroasiatic theoretically plausible, but that any demonstration of it by lexical comparison remains "almost by definition impossible", due to the reconstruction of Proto-Afroasiatic being still poorly developed.

There are no dialects, though there is some regional vocabulary, especially Bantu loans, which are more numerous in the southern and western areas of high bilingualism.^{[citation needed]}

The language is marked as "threatened" in Ethnologue.

Hadza syllable structure is limited to CV, or CVN if nasal vowels are analyzed as a coda nasal. Vowel-initial syllables do not occur initially, and medially they may be equivalent to /hV/ – at least, no minimal pairs of /h/ vs zero are known.^{[citation needed]}