In linguistics, an areal feature is any typological feature shared by languages within the same geographical area. Linguistics is the scientific study of human language, and someone who engages in this study is called a linguist or linguistician. ... Linguistic typology is the typology that classifies languages by their features. ...

Resemblances between two or more languages (whether typological or in vocabulary) can be due to genetic relation (descent from a common ancestor language), or due to borrowing at some time in the past between languages that were not necessarily genetically related. When little or no direct documentation of ancestor languages is available, it can be hard to determine whether a similarity is genetic or areal. Genetic, in linguistics, means due to descent from a common ancestor language, rather than borrowing at some time in the past between languages that were not necessarily descended from a common ancestor. ... A loanword is a word directly taken into by one language from another with little or no translation. ...

Examples include the prevalence of contrasting phonemic tone in East and Southeast Asia, which may have started with the Miao-Yao or Tai-Kadai languages; the occurrence of click consonants in Bantu languages of southern Africa, which originated in the Khoisan languages; the lack of a [p] in many of the languages around the Sahara, such as Arabic; the lack of fricatives in Australian languages; the prevalence of ejective lateral affricates in the Pacific Northwest of North America; the spread of the uvular R from French to several Germanic languages; the use of the plural pronoun as a polite word for you in much of Europe (the tu-vous distinction); and the spread of a verb-final word order to the Austronesian languages of New Guinea. This article or section uses Ruby annotation. ... The Hmong-Mien or Miao-Yao languages are a language family of southern China and Southeast Asia. ... The Tai-Kadai languages are a language family found in Southeast Asia and southern China. ... Clicks are stops produced with two articulatory closures in the oral cavity. ... Map showing the distribution of the Khoi-San languages. ... Arabic (; , less formally, ) is the largest member of the Semitic branch of the Afro-Asiatic language family (classification: South Central Semitic) and is closely related to Hebrew and Aramaic. ... Fricatives (or spirants) are consonants produced by forcing air through a narrow channel made by placing two articulators close together. ... The Australian Aboriginal languages are a Australia, and the rest are descended linguistically from them. ... Ejective consonants are a class of consonants which may contrast with aspirated or tenuis consonants in a language. ... A lateral affricate is an affricate with a lateral consonant. ... Uvulars are consonants articulated with the back of the tongue against or near the uvula, that is, further back in the mouth than velar consonants. ... The Germanic languages form one of the branches of the Indo-European (IE) language family. ... In sociolinguistics, a T-V distinction describes the situation wherein a language, unlike current English, has pronouns that distinguish varying levels of politeness, social distance, courtesy, familiarity, or insult toward the addressee. ... In linguistic typology, Subject Object Verb (SOV) is the type of languages in which the subject, object, and verb of a sentence appear (usually) in that order. ... The Austronesian languages are a language family widely dispersed throughout the islands of Southeast Asia and the Pacific, with a few members spoken on continental Asia. ...

But French and German ARE related, as are European languages using the tu/vous distinction. The influence of Arabic on Spanish would be a better example of an areal feature spanning genetically unrelated languages.

Bibliography

• Campbell, Lyle. (In press). Areal linguistics. In K. Brown (Ed.), Encyclopedia of language and lingustics (2nd ed.). Oxford: Elsevier. (Online version: http://www.linguistics.utah.edu/Faculty/campbell/CampbellArealLingEnc.doc).