ranĉo

Note the hat. Ranĉo is written with ĉ, and the x-system slug for it is rancxo, because the Spanish ch sound is exactly what ĉ is for. Getting this wrong and writing ranco gives you a different word entirely: ranca is rancid.

Ranĉo is a specifically New World kind of farm, the cattle-and-horses sort with a lot of land. The general word is bieno, an estate or farm of any kind, and that is what you want for a European smallholding. Esperanto borrowed ranĉo for the same reason English did, because there was no European word for the thing.

It is a good demonstration that the language is not confined to Latin and Greek. Zamenhof's rule was to take the most internationally recognisable form, and by the twentieth century rancho had travelled far enough on the back of American westerns to qualify. The same logic later brought in kaŭboj, ĝangalo and bumerango.