The Dhao language, better known to outsiders by its Rotinese name Ndao (Ndaonese, Ndaundau), is the language of Ndao Island in Indonesia. Traditionally classified as a Sumba language in the Austronesian family, it may actually be a non-Austronesian (Papuan) language. It was once considered a dialect of Hawu, but is not mutually intelligible.

Dhao phonology is similar to that of Hawu, but somewhat more complex in its consonants.

Consonants of the /n/ column are apical, those of the /ɲ/ column laminal. /f w j/ are found in Malay loan words. In a practical orthography developed for writing the language, implosives are written ⟨b' d' j' g'⟩, the affricates ⟨bh dh⟩ (the dh is slightly retroflex), and the voiced glottal onset as a double vowel. The /ʕ/ is sometimes silent, but contrasts with a glottal stop onset in vowel-initial words within a phrase. Its phonemic status is not clear. It has an "extremely limited distribution", linking noun phrases (/ʔiki/ 'small', /ʔana ʕiki/ 'small child') and clauses (/ʕaa/ 'and', /ʕoo/ 'also').

Vowels are /i u e ə o a/, with /ə/ written ⟨è⟩. Phonetic long vowels and diphthongs are vowel sequences. The penultimate syllable/vowel is stressed. (Every vowel constitutes a syllable.)

/ŋe/ [ŋe] 'this.OBJ', /neʔe/ [ˈneʔe] 'this', /ŋaŋee/ [ŋaˈŋeː] 'thinking', /ŋali/ [ˈŋali] 'senile', /ŋəlu/ [ˈŋəlːu] 'wind'.

A stressed schwa lengthens the following consonant: /meda/ [ˈmeda] 'yesterday', /məda/ [ˈmədːa] 'night'.

Syllables are consonant-vowel or vowel-only.

f, q, v, w, x, y and z are only used in loanwords and foreign names.