～国
～こく · ～koku · JLPT N2 · noun
nation of ~
🏳️ 国 = 囗 border + 玉 jewel: a jewel kept inside a border, so a nation
As a suffix, ～国 (koku) turns a name into a country: 米国 beikoku is the USA, 外国 gaikoku is a foreign country. After some sounds it changes to goku, as in 中国 chuugoku, China.
国 — enclosure 囗 + jade 玉
国 is a simplified form of 國. The outer 囗 represents borders or an enclosed territory, while the inner 玉 (jade) suggests a treasured realm ruled by a sovereign. The traditional 國 used 或 inside, depicting a guarded region with a weapon, later simplified by replacing it with 玉.