A restatement of another writer's text that uses too much of the original vocabulary and syntax.
These days, it feels like hardly a week goes by without a professional journalist being exposed for plagiarism, fabrication or patchwriting, which is a failed attempt at paraphrasing that over-relies on the original writer's syntax and vocabulary. That last transgression is likely today's most common sin, according to Rebecca Moore Howard, the Syracuse University professor of writing and rhetoric who coined the term.
—Kelly McBride, "Journalism's problem is a failure of originality," The Globe and Mail, September 28, 2012
Of the 1,911 student uses of sources that the project coded,...16% are "patchwritten," defined as "restating a phrase, clause, or one or more sentences while staying close to the language or syntax of the source"...
Worse, our adherence to the received definition of plagiarism blinds us to the positive value of a composing strategy which I call "patchwriting": copying from a source text and then deleting some words, altering grammatical structures, or plugging in one-for-one synonym substitutes.
—Rebecca Moore Howard, "A Plagiarism Pentimento," Journal of Teaching Writing, June 1, 1993 (approx)
The current uses of the word patchwriting are almost always negative and view such writing as a lightweight form of plagiarism. However, as you can see with the earliest citation, the coiner of the term viewed such writing as positive: it is (she goes on the say) "a valuable composing strategy in which the writer engages in entry-level manipulation of new ideas and vocabulary."