German linguist, a pioneer in Indo-European (Indo-European languages) etymological research who made the first comprehensive study of the common vocabulary of Indo-European languages and sought to determine their prototype.

Fick presented his reconstruction of a parent language of remote prehistoric times in the first edition of his major work (1868), later titled Vergleichendes Wörterbuch der indogermanischen Sprachen (“Comparative Dictionary of the Indo-European Languages”), emphasizing the lexical comparison of ancient recorded languages. Another important work, Die griechischen Personennamen nach ihrer Bildung erklärt . . . (1874; “Greek Proper Names As Explained by Their Formation . . .”), showed similarities in the formation of Greek names and those of the other Indo-European languages, except Latin. This demonstration suggested the concept of the original Indo-European community as a stable aristocracy whose descendants became rulers of the Greek, Hindu, Iranian, Celtic, Germanic, and other major civilizations of antiquity.

In 1876 Fick became professor at the University of Göttingen and then at the University of Breslau (modern Wrocław, Pol.; 1888–91). Though ill health compelled him to retire, he continued private research. His lucid presentation and his orderly grasp of an immense repertory of facts made his writings useful for more than a generation, and much of his research was incorporated rather than superseded by later researchers.