Dyirbal (also Djirubal) is a tonal and ergative Australian Aboriginal language spoken in northeast Queensland by about 5 speakers. It possesses many outstanding features that have made it well known among linguists.

Phonology

Dyirbal actually has only four places of articulation for the stop and nasal consonants—this is fewer than most other Australian Aboriginal languages, which have six. This is because Dyirbal lacks the dental/alveolar split typically found in these languages. It also lacks voiceless consonants, an extremely uncommon trait among languages. Its vowel system is similarly small, with only three vowels: /i/, /a/ and /u/.

Grammar

The language is best known for its system of noun classes, numbering four in total. They tend to be divided among the following semantic lines:

• I - animate objects, men
• II - women, water, fire, violence
• III - edible fruit and vegetables
• IV - miscellaneous (includes things not classifiable in the first three)

The class usually labeled "feminine" (II), for instance, includes the word for fire and nouns relating to fire, as well as all dangerous creatures and phenomena. This inspired the title of the George Lakoff book "Women, Fire and Dangerous Things". Some linguists distinguish between such systems of classification and the gendered division of items into feminine, masculine, and sometimes neuter found in, for example, many Indo-European languages.

Dyirbal is remarkable because it shows a split-ergative system. Sentences with a first or second person pronoun have their verb arguments marked for case in a pattern that mimics nominative-accusative languages. That is, the first or second person pronoun appears in the least marked case when it is the subject (regardless of the transitivity of the verb), and in the most marked case when it is the direct object. Thus Dyirbal is morphologically accusative in the first and second persons, but morphologically ergative elsewhere; and it is still always syntactically ergative.

Taboo

There used to be in place a highly complex taboo system in Dyirbal culture. A speaker was completely forbidden from speaking with his/her mother-in-law, child-in-law, father's sister's child or mother's brother's child, and from approaching or looking directly at these people. In addition, a specialized and complex form of the language, with essentially the same phonemes and grammar, but with a lexicon that shared no words with the non-taboo language, was used when within hearing range of taboo relatives. It existed until about 1930 when the taboo system fell out of use.