In a way that has to do with syntax — that is, with how words are put in order to make a sentence, and how the parts of a sentence fit together. If you say a sentence is 'syntactically correct', you mean the word order and the grammar of the sentence follow the rules, even if you say nothing at all about whether the sentence makes sense. This is the useful thing about the word: it lets you praise or criticise only the structure. Chomsky's famous example, 'Colorless green ideas sleep furiously', is syntactically perfect and completely meaningless — that is exactly the gap the word exists to point at. You will meet it mostly in three places: language teaching and linguistics ('these two sentences are syntactically the same'), computer programming ('the code is syntactically valid but it does the wrong thing' — programmers use it constantly), and careful writing about writing. It is a formal, academic word; in ordinary talk people just say 'the grammar is fine' or 'the word order is wrong'. Note that it often comes with a quiet 'but' after it. When someone says 'syntactically, yes…', they are usually about to tell you that something else is wrong.

在句法上、就句法/句型結構而言（台灣語言學與程式領域都常說「語法上」）。注意：中文的「語法」有時包含詞形變化等更廣的東西，而 syntactically 只管詞序與句子結構這一塊。