User:Tropylium/List of Proto-Indo-European roots by distribution

Proto-Indo-Hittite roots
Roots with reflexes attested from the Anatolian languages.

West-Central Indo-European roots
Roots unattested from Anatolian, Tocharian and Indo-Iranian.

East-Central Indo-European roots
Roots unattested from Anatolian, Tocharian, Celtic and Italic.

Central Indo-European roots
Roots unattested from Anatolian, Tocharian, Celtic, Italic, and Indo-Iranian.

"West Centum" roots
Roots attested only in Germanic, Celtic and/or Italic.

Northwestern Indo-European roots
Roots attested only in Germanic and Balto-Slavic.

Indo-Greek roots
Roots attested only in Greek, Armenian, and/or Indo-Iranian.