By comparing the recorded Indo-European languages, especially the most ancient ones, much of the parent language from which they are descended can be reconstructed. This reconstructed parent language is sometimes called simply Indo-European, but in this article the term Proto-Indo-European is preferred.

That system had developed from Proto-Indo-European plain consonants and some clusters as a result of palatalization processes as well as the so-called consonant shift, a process including the devoicing of Proto-Indo-European voiced consonants. The consonant shift in Proto-Armenian had some similarities to the Proto-Germanic shift (see Grimm’s law), although these…

…which the name Indo-European or Proto-Indo-European is now customarily applied. That all the Romance languages were descended from Latin and thus constituted one “family” had been known for centuries; but the existence of the Indo-European family of languages and the nature of their genealogical relationship was first demonstrated by the…

…the voiced stops inherited from Proto-Indo-European became voiceless and the voiceless stops became fricatives. The situation with respect to the sounds corresponding to the Germanic voiced stops is more complex. Here there is considerable disagreement between the other languages: Greek has voiceless aspirates (ph, th), Sanskrit has voiced aspirates (bh,…

…(Grimm’s law), which turned a Proto-Indo-European dialect into a new Proto-Germanic language within the Indo-European language family. The Proto-Indo-European consonants p, t, and k became the Proto-Germanic f, [thorn] (th), and x (h), and the Proto-Indo-European b, d, and g became Proto-Germanic p, t, and k. The historical context of…

…which can be reconstructed as Proto-Indo-European (see Indo-European languages).

…referred to as “Indo-European,” “Proto-Indo-European,” the “common parent language,” or the “original language” (Ursprache) of the family. But it must be emphasized that, whatever it may have been like, it was just one language among many and of no special status in itself. It was certainly in no way…

…worked out in detail for Indo-European during the latter part of the 19th century. It rests on the assumption that sound correspondences in related words and morphological units, as well as structural similarities on all levels (phonology, morphology, syntax), can be explained in terms of a reconstructed common language, or…