外がい核かくがいかくMeanings1nounouter coregeologyGeology term referring specifically to the liquid outer core of the Earth, often contrasted with 内核 (inner core).See also: 内核地ち球きゅうの外がい核かくは液えき体たいの鉄てつでできていると考かんがえられている。The Earth's outer core is thought to be made of liquid iron.