PLAGIARISM
Plagiarism is claiming (or appearing to claim} someone else's work as one's own. It can take many forms, some of which are obviously dishonest and some of which seem to be dishonest even though they may result from a genuine ignorance of how one may use others' ideas but still produce honest work.
Unfortunately dishonesty does persist into the college years. But ignorance at least can be eliminated by understanding what practices are considered plagiaristic by studying illustrative examples and by consulting one's instructor when in doubt.
Plagiarism is involved in all of the following practices:
1. Directly copying all or parts of a paper without using quotation marks and scrupulously acknowledging the sources.
2. Submitting a paper someone else has written whether that paper has been bought or borrowed or written for the student by an articulate friend.
3. Using another's phrasing with occasional slight modification but without quotation marks to indicate the unchanged phrasing even though a footnote indicates the source of ideas.
4. Using someone else's striking phrasing without quotation marks in a paper which is mostly original. (The key terms pertaining to the subject however can and should be used freely by all who write about the subject.}
5. Using someone else's organizational pattern without acknowledgement except for an inherent pattern like chronology. (Even with acknowledgement a borrowed pattern may suggest insufficient thought about the subject.}
6. Using someone else's illustrative analogies, allusions or other figures of speech as if they were one's own. (Using the same examples is also dubious and in addition suggests that the student does not understand the subject clearly enough to think of examples of his own.)
7. Presenting someone else's opinions as one's own or borrowing specific facts without acknowledging the sources.
In addition to those using the same paper for more than one course without the explicit approval of the instructors involved is academically dishonest even though the paper is entirely original, for it deliberately misleads the instructors as to the amount of work done and the amount of knowledge gained. It is perhaps not plagiarism but it is obtaining credit (in two senses of the word) under false pretenses.
(Courtesy of Robert Moore from his book Effective Writing.}