An offprint is one article taken from a magazine or a journal and printed on its own, as a thin separate copy. Universities and researchers use this word a lot. After a paper comes out in a journal, the writer may get offprints to give to colleagues — just that article, not the whole issue. It is not a new book, and it is not a photocopy from the library machine; it is that one piece, printed off from the larger work. People sometimes sell such copies, but in academic life they are often given away. There is also a verb, to offprint, meaning to print something this way, but the noun is what you will meet. It is a specialist word, at home in libraries and academic mail, not in everyday talk.

抽印本（期刊裡的一篇另行印成單篇，學術界常用）