Théorie des vaguesvignette|367x367px|Schéma basé sur le modèle de vagues présenté à l'origine par Johannes Schmidt.Ce diagramme d'Euler doit se lire comme une carte géographique, ou plus précisément dialectologique. Chaque cercle représente une innovation linguistique, comme des isoglosses sur une carte dialectale. À mesure qu'une innovation se répand dans le continuum dialectal, les cercles augmentent de diamètre au fil du temps, comme des “ondes” ou “vagues” sur la surface de l'eau frappée par une pierre.
Daughter languageIn historical linguistics, a daughter language, also known as descendant language, is a language descended from another language, its mother language, through a process of genetic descent. If more than one language has developed from the same proto-language, or 'mother language', those languages are said to be sister languages, members of the same language family. These concepts are linked to the tree model of language evolution, in which the relationships between languages are compared with those between members of a family tree.
Language convergenceLanguage convergence is a type of linguistic change in which languages come to resemble one another structurally as a result of prolonged language contact and mutual interference, regardless of whether those languages belong to the same language family, i.e. stem from a common genealogical proto-language. In contrast to other contact-induced language changes like creolization or the formation of mixed languages, convergence refers to a mutual process that results in changes in all the languages involved.
Father Tongue hypothesisThe Father Tongue hypothesis proposes that humans tend to speak their father's language. It is based on a 1997 proposal that linguistic affiliation correlates more closely with Y-chromosomal variation than with mitochondrial DNA variation. The initial work was performed on African and European samples by a team of population geneticists led by Laurent Excoffier. On the basis of these and similar findings by other geneticists, the hypothesis was elaborated by historical linguist George van Driem in 2010 that the teaching by a mother of her spouse's tongue to her children is a mechanism by which language has preferentially been spread over time.
Similarité lexicaleEn linguistique, la similarité lexicale est la mesure du degré de ressemblance entre des séries de mots appartenant à deux langages donnés. Une similarité lexicale de 1 (ou 100 %) correspondrait à un recouvrement total entre les vocabulaires, tandis que 0 signifie qu'il n'y a pas de mots communs. Il y a plusieurs façons de définir la similarité lexicale et les résultats varient en conséquence. Par exemple, la méthode de l’Ethnologue consiste à comparer un ensemble standardisé de listes de mots et à compter les formes qui présentent une similitude à la fois dans la forme et dans la signification.
Langue vivanteUne langue est vivante lorsqu'elle est parlée actuellement par des locuteurs qui l'utilisent spontanément pour la communication interpersonnelle. Le terme s'oppose à celui de langue morte. Les langues jouent un rôle essentiel dans la vie des sociétés. Au sein d’une population, elles permettent, parmi plusieurs moyens, de transmettre et donc de partager une culture. En effet, par l’intermédiaire de sa langue, l’homme exprime une façon de comprendre le monde forgée par son histoire, ses traditions et croyances, ses relations culturelles, politiques et économiques.
Attested languageIn linguistics, attested languages are languages (living or dead) that have been documented and for which the evidence (“attestation”) has survived to the present day. Evidence may be recordings, transcriptions, literature or inscriptions. In contrast, unattested languages may be names of purported languages for which no direct evidence exists, languages for which all evidence has been lost, or hypothetical proto-languages proposed in linguistic reconstruction.
Linkage (linguistics)In historical linguistics, a linkage is a network of related dialects or languages that formed from a gradual diffusion and differentiation of a proto-language. The term was introduced by Malcolm Ross in his study of Western Oceanic languages . It is contrasted with a family, which arises when the proto-language speech community separates into groups that remain isolated from each other and do not form a network. Linkages are formed when languages emerged historically from the diversification of an earlier dialect continuum.
