- something filled with, a container or box for, e.g. inko (“ink”) → inkujo (“inkpot”).
- (only official) a country inhabited by, or associated with, an ethnic group, e.g. turko (“Turk”) → Turkujo (“Turkey”).
- (obsolete) a tree bearing a fruit, e.g. pomo (“apple”) → pomujo (“apple tree”).
The differences between -uj- and -ing- is that -ing- can only contain a single object or part of an object, such as a glavingo (“scabbard”) (the entire sword isn't inside the holder for example, and it can only hold one sword), plumingo (“pen holder”), or kandelingo (“a candlestick”), or fingringo (“a thimble”). An -uj- is a container for multiple objects, for example something you replenish or keep in quantity, and it usually contains things in their entriety, such as a cigarujo (“cigar box”) or sukerujo (“sugar bowl”).
-uj- is almost never used for names of fruit trees outside of early Esperanto writings. This archaic usage comes directly from the Fundamento de Esperanto, but has been nearly entirely supplanted by compounds ending in arbo (“tree”) or arbusto (“bush”), such as pomarbo (“apple tree”).
Some countries in Europe and Asia have Esperanto names using -uj-. These names, though less used, are still the sole official forms.
- Ido: -uyo