one country; a single nation
Refers to one country as a unit, often in political or comparative contexts.
As the prime minister of one country, he feels a sense of responsibility.
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).
The whole nation was enveloped in a celebratory mood.
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
He has a stubborn personality and doesn't listen to others.
The whole nation cheered on the Olympics together.
The king has governed the country for many years.
He quit his company, went independent, and became the master of his own domain.
one country, two systems
one-party system
socialism in one country; one-state socialism