Gxis
Can be translated as "unto", as it applies to both time and place. It can thus translate as "until", "up to", "as far as", or "through" (when describing a range). A very common farewell among Esperanto speakers is gxis revido, literally "until the re-sight.
Information provided by the Esperanto HyperCourse Maintainer as part of the Esperanto HyperCourse.