各国 literally means 'each country' or 'various countries', formed by 各 (gè, 'each; every') and 国 (guó, 'country; nation'). It functions as a collective noun referring to multiple countries simultaneously—often in contexts involving international relations, global comparisons, or cross-national phenomena. Unlike the singular 国 or plural 国家们 (which is rarely used), 各国 emphasizes diversity and plurality without specifying exact numbers.

This term commonly appears in formal, written, or news-oriented Chinese—such as reports on diplomacy, trade, education exchanges, or environmental policy. It carries a neutral, inclusive tone and implies breadth rather than exclusivity: for example, 各国政府 ('governments of various countries') suggests cooperation across national boundaries. While grammatically plural, it does not take plural markers like 们, nor does it require a classifier—it stands alone as a compound noun.