An adverb meaning 'in a transitive way'. In grammar, it describes a verb being used WITH an object: 'break' is used transitively in 'I broke the cup', because the breaking lands on something. Used intransitively, the same verb takes no object: 'The cup broke.' The adverb is mostly a grammar-book and teacher's word — 'this verb is normally used transitively', 'here, run is used transitively: she runs a restaurant'. You will meet it in dictionaries, in grammar explanations, and in your teacher's speech, not in conversation. There is a second, quite separate life in mathematics and logic, where a relation is transitive if it carries through a chain: if A equals B and B equals C, then A equals C 'transitively'. Programmers borrow that sense too — a 'transitively required' library is one your library needs, so you end up needing it as well. Same underlying picture in both: something passing across from one thing to the next.

（文法）作及物動詞用地；（數學／邏輯）遞移地、傳遞地。台灣文法課直接講「及物」「當及物動詞使用」，很少把副詞形譯出來；數學課則說「遞移律」（transitive）。