Is it farther or further?
1814, coined by physician, physicist and Egyptologist Thomas Young (1773-1829) and first used in an article in the "Quarterly Review," from Indo-, comb. form of Greek Indos "India" + European. "Common to India and Europe," specifically in reference to the group of related languages and to the race or races characterized by their use. The alternative Indo-Germanic (1835) was coined in German 1823 (indogermanisch), based on the two peoples at the extremes of the geographic area covered by the languages, before Celtic was realized also to be an Indo-European language. After this was proved, many German scholars switched to Indo-European as more accurate, but Indo-Germanic continued in use (popularized by the titles of major works) and the predominance of German scholarship in this field made it the popular term in England, too, through the 19c. See also Aryan.