Je
A vague preposition that describes some sort of relation between two objects. It is usually "safe" to use je when no other preposition clearly carries the desired meaning: "I believe IN God", "laugh AT him". Especially used to translate "at" in time-of day expressions like "he will arrive AT 4:00".
Information provided by the Esperanto HyperCourse Maintainer as part of the Esperanto HyperCourse.