俄国(é guó) - Russia, the Russian state in Mandarin

俄国 (é guó) is Russia. It is built the way every short country name in Chinese is built: take one syllable from the transliteration and bolt 国 on the end, exactly as 美国, 英国, 法国 and 德国 are formed.

俄国 and 俄罗斯 both mean Russia, but they are not interchangeable in tone. 俄罗斯 is the formal modern name of the country and the one you will see on the news. 俄国 leans historical and general, and it is the form that dominates in writing about the tsars, the nineteenth-century novelists and old wars.

The trap is the adjective. English needs a separate word, Russian, but Chinese just puts the country name in front of the noun: 俄国人 is a Russian, 俄国历史 is Russian history, 俄国菜 is Russian food. Note the odd man out too: the language is 俄语 or 俄文, never 俄国语.