refers to a large family of languages that includes English, most of the languages of modern Europe, Greek, Latin, Persian, and Sanskrit, the sacred tongue of ancient India. (p. 22)
Prehistoric "parent" language from which a large set of European and western Asian languages developed. Sir William Jones proposed this relationship in 1786 after observing common elements between Sanskrit, Latin, and Greek. Included in this family are the Germanic, Celtic, Italic, Hellenic, Balto-Salvic, Indo-Iranian, and other language families. Not included are three European languages (Finnish, Hungarian, and Basque), African languages, North American Native languages, and many Asian languages such as Arabic, Japanese, and Chinese. Using the comparative method to reconstruct the proto-IE lexicon, linguists have argued for south central Europe (southern Russia) as the home of the Indo-Europeans before the migrations that developed separate descendant languages; anthropologists and archeologists research this Kurgan culture. An appendix of The American Heritage Dictionary gives many of these reconstructed roots, and its CD-ROM version, a root is sometimes give after the entry of a PDE word that developed from it.