Lett

from The Collaborative International Dictionary of English v.0.48

Letts \Letts\ (l[e^]ts), n. pl.; sing. {Lett} (l[e^]t).
   (Ethnol.)
   An Indo-European people, allied to the Lithuanians and Old
   Prussians, and inhabiting a part of the Baltic provinces of
   Russia.
   [1913 Webster]