outermost

outermost
/ˈautəməust; `aʊtɚˌmost/ adj
farthest from the inside or centre; most remote 最外面的; 远离中心的
    the outermost planet from the sun 离太阳最远的行星
    the outermost districts of the city 城市的偏远地区.

牛津英汉双解词典