Each word in Ido comes from a smaller word called a "root word". A root word has a root and an ending. The speaker can take the root and put it on another word to make a new one. For example, "urbo" means "city" and "-estro" means "leader". The root of "urbo" is "urb-", and if -estro is put on the end, it becomes "urbestro", which means mayor (leader of a city). Or the speaker can put something on before; chef- means chief or leader, and if the speaker puts that before the word it becomes "chefurbo", which means capital city.