Definition - Another name for Indo-European, the name of the family of cognate languages and dialects that includes most of the languages of Europe, as well as many in Asia.

1. A student of Indo-Germanic philology is called an Indo-Germanist.

Etymology -
According to the OED:
"Indo-Germanic is a term of later introduction than Indo-European, and of German origin, appearing first, so far as yet traced … in Klaproth Asia Polyglotta, 1823. With Klaproth it seems to have been a kind of abbreviation of the expression (used by him in an earlier work) ‘die grosse Indisch-Medisch-Sclavisch-Germanische Völkerkette, die vom Ganges bis zu den Britannischen Inseln reicht’, naming the two extreme members of the ethnological ‘chain’.

When Celtic was shown to be a still more extreme member of the same series, indogermanisch lost its appropriateness, and some scholars tried to substitute indokeltisch, Indo-Celtic … while others, as Bopp in his Vergleichende Grammatik, gave preference to the more comprehensive indoeuropäisch, the equivalents to which, Indo-European, indo-européen, were also favoured in Great Britain and France.

But the employment of indogermanisch on the title-page of Pott's Etymologische Forschungen auf dem Gebiete der indogermanischen Sprachen (1833–36) popularized this term in Germany, whence under the influence of German textbooks, or of teachers trained in Germany, it came into English use, and was, in the 19th c., probably more used than Indo-European."

Oxford English Dictionary -
Its first citation is from 1835:
"The family of the Indo-Germanic languages may, according to Mr. Pott, be divided into five branches."
([Dr. Rosen] in Q. Jrnl. Educ. Apr. 332 (Review of Pott),)

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