This is the 412th most frequent Japanese word.
国家
"国家" means "nation" or "state."
Here, 国家 is used to refer to the 'nation' as a whole entity or political organization.
国家は国民を守る義務があります。
The nation has a duty to protect its citizens.
In this case, 国家 emphasizes the characteristic or identity of the 'nation' as a unique entity.
日本は島国として独特な国家です。
Japan is a unique nation as an island country.
Here, 国家 is used to describe the scale or scope related to the 'national' level of operations or considerations.