1The official language of a country; in Japan this generally refers to Japanese itself.
その国では国語として二つの言語が公認されている。
In that country, two languages are officially recognized as national languages.
憲法には国語についての規定がない国も多い。
Many countries have no provision in their constitution regarding a national language.
2'Kokugo,' the Japanese-language subject taught in Japanese schools, covering reading comprehension, composition, kanji, and so on.
弟は国語のテストで漢字を書き間違えた。
My younger brother wrote a kanji wrong on his kokugo test.
今日の国語の授業では詩を音読した。
In today's kokugo class we read a poem aloud.
彼女は国語の先生になるために教育学部に進んだ。
She entered the faculty of education to become a kokugo teacher.
3The language a person first learned and normally uses; one's mother tongue.
移民二世の彼にとって国語は両親の母国語ではなく日本語だ。
For him, a second-generation immigrant, his native language is Japanese, not his parents' mother tongue.
国語が異なる夫婦は家庭内で通訳アプリを使うこともある。
Couples whose native languages differ sometimes use a translation app at home.
4Sometimes refers to native Japanese vocabulary (wago), as distinguished from Sino-Japanese words and loanwords.
「山」や「川」は国語、つまり和語に分類される。
Words like 「山」 and 「川」 are classified as native Japanese (wago) vocabulary.
辞書では国語と漢語を区別して語源が示されている。
Dictionaries indicate the etymology, distinguishing native Japanese words from Sino-Japanese ones.