Avoidance speech, or "mother-in-law languages", is a feature of many Australian Aboriginal languages and some North American languages whereby in the presence of certain relatives it is taboo to use everyday speech style, and instead a special speech style must be used. The Australian Aboriginal languages comprise several language families and isolates native to Australia and a few nearby islands, but by convention excluding Tasmania. ... A taboo is a strong social prohibition (or ban) relating to any area of human activity or social custom declared as sacred and forbidden; breaking of the taboo is usually considered objectionable or abhorrent by society. ...

Avoidance speech styles tend to have the same phonology and grammar as the standard language they are a part of. The lexicon, however, tends to be smaller than is normal speech, since it only needs to be used when conversation with the taboo relatives is absolutely necessary. The vowels of modern (Standard) Arabic and (Israeli) Hebrew from the phonological point of view. ... Grammar is the study of rules governing the use of language. ... Look up lexicon in Wiktionary, the free dictionary. ...

For instance, in Dyirbal there is the regular speech style (called Guwal) and the avoidance style Dyalngui consisting of a special set of lexical items that are substituted for Guwal words in the presence of opposite-sex parents-in-law, opposite-sex children-in-law, and opposite-sex cross-cousins. These words are fewer, however, and their meanings tend to be much more generic, e.g. the Dyalngui verb bubaman does service for the Guwal verbs baygun "shake", dyindan "wave" and banyin "smash". Dyirbal (also Djirubal) is a tonal and ergative Australian Aboriginal language spoken in northeast Queensland by about 5 speakers. ... Cross Cousin is an anthropological term describing kin who are in the same descent group as the subject (ego) and are from the parents opposite-sexed sibling. ...

External links

• Lecture notes on Dyirbal illustrating mother-in-law language
• One of three "LanguageHat" blog posts in the topic