noun
one country; a single nation
Refers to one country as a unit, often in political or comparative contexts.
一国の首相として、彼は責任を感じている。
As the prime minister of one country, he feels a sense of responsibility.
noun
the whole nation; the entire country
Used when referring to the country as a whole, often in expressions like 一国を挙げて (the whole nation).
一国を挙げて祝賀ムードに包まれた。
The whole nation was enveloped in a celebratory mood.
na-adjective
Dated adjectival noun usage; now more commonly written as 一刻 (いっこく). The cross-reference in This is the same word as 一刻・2.
See also: 一刻
彼は一国な性格で、人の言うことを聞かない。
He has a stubborn personality and doesn't listen to others.