国家

国家 (guójiā) means a 'country' or 'nation' — a sovereign political entity with land, people, and government. It is the standard everyday word for 'country' (我去过五个国家 — I've been to five countries) and also covers 'state' in the sense of nation-state (国家政策 — national / state policy). The two characters together originally meant 'country and family,' reflecting the old idea that a nation is an extended household. Two notes for English speakers: first, when you want to say someone's home country, 国家 is fine, but Chinese also has 祖国 (zǔguó — 'motherland / homeland') for an emotional, patriotic sense.

Second, for the U.S. 'state' as in Texas or California, use 州 (zhōu); 国家 specifically means an independent country, not a sub-unit. As a modifier ('national'), 国家 + noun is extremely productive: 国家队 (national team), 国家公园 (national park).