Yǔfǎ
Reading Ōshima Shōji 大島正二's Chūgokugo no rekishi 中国語の歴史 ("History of the Chinese language"), I came across an interesting comment on the Chinese word for "grammar."
As any fule know, the word for "grammar" in Japanese is bunpō 文法 ("sentence/writing rules"). Its use as a term of art in the field of linguistics dates from the 19th century, but the two-character combination has been around for much longer with related but premodern meanings (e.g. in the 17th C. Nippo Jisho 日葡辞書 it's defined as the rules for writing letters correctly). I don't have a cite, but it seems likely to me that in this sense it goes back to Chinese.
However, the standard word for "grammar" in contemporary Mandarin is yǔfǎ 语法 ("word rules"). This word is also in Japanese, but with a much more restricted meaning: the rules for manipulating and using individual words, not for combining them into sentences.
Ōshima points out that there was a time when 文法 was used in Chinese too, as can be seen from the very titles of books like Lí Jǐnxī 黎锦熙's 1924 Xīnzhe guóyǔ wénfǎ 新著国語文法 ("New grammar of the national language"). Around 1942-1943, though, books began appearing with 语法 (well, at the time, 語法) in the title instead.
Zhōngguó xiàndài yǔfǎ 中国現代語法 ("Contemporary Chinese grammar"), by Wáng Lì 王力, was one such book. According to Ōshima, Wáng explained his use of 語法 as follows: of the three words in current usage, 文法 refers properly to written language and 話法 ("speech rules") refers to spoken language. Only 語法 can refer to either, and therefore it is the best neutral term for "grammar".
Ōshima speculates that the triumph of 语法 may reflect the Chinese view of grammar as something that boils down to the correct arrangement and use of (fixed, atomic) words — as opposed to, for example, the Indo-European and even Japanese model where the words themselves change according to their role in the sentence — but I don't know enough about Chinese attitudes towards their own language to assess that hypothesis.
minus273:
Except for the fact that words are not called 语 in Chinese. 单语 a couple of times maybe, but never 语. The standard term is 词(儿). The 语-文 opposition is instead focused on the relation between spoken and written language.