From Wiktionary, the free dictionary
᠊ᠮᠰᡳ • (-msi)
- Used to form nouns both from verbs and nouns, designating people according to their skills, occupations, ranks, trades, and business
- ᡨᠠᠴᡳ᠊ (taci-, “to study”) + ᠊ᠮᠰᡳ (-msi) → ᡨᠠᠴᡳᠮᠰᡳ (tacimsi, “student of the National Imperial Academy”)