If a man plagiarizes by copying from other peoples' work, what do we call the document (e.g. research paper) that he creates based on this, which contains the copied research?
As Pickett’s answer says, plagiarism itself can be used in this sense.
If you wish to distinguish between plagiarism (the act or practice of plagiarising content) and the resulting work, however, there is another word which can be called upon: plagiary.
Most dictionaries define plagiary as:
- Plagiarist; one that plagiarises
The first sense is archaic, and noted as such in dictionaries; but the second sense is synonymous with plagiarism. You can use this to deliberately distinguish between the two meanings. A similar double meaning is found for forgery, which can both be the action and the work, but forgery is used more often for the work than the action (where a gerund forging is more prevalent); for this reason, I would suggest using plagiarism for the action, and plagiary for the work.
Note, however, that there is no hard-and-fast distinction between the words, so you’ll have to specify that you are using the words deliberately in this way.
(Side note: the word plagiat does exist in English, too, though it’s very rare and archaic. Don’t use that, though: it means kidnapping in English!)
English does not have a single word that expresses the concept 'the piece of text that was plagiarized'. One might use 'a plagiarism' to attempt to capture this but it would be very infelicitous (it would sound off and would be difficult to understand that way).
The shortest clear way to express it is to say it is with two words:
For other media, there are single words. In art, one uses 'fake' ("that painting is a fake"). In music, one can use 'sample' but that word has removed the taboo connotation with stealing.