*lettic*

a. (a) Of or pertaining to the Letts; Lettish. (b) Of or pertaining to a branch of the Slavic family, subdivided into Lettish, Lithuanian, and Old Prussian. -- n. (a) The language of the Letts; Lettish. (b) The language of the Lettic race, including Lettish, Lithuanian, and Old Prussian. [ 1913 Webster ]