Taken from the Latin words plagiaries, meaning plunderer, and plagium, meaning kidnapping, plagiarism means "to steal and use (the ideas or writings of another) as one's own," according to The American Heritage Dictionary, second edition. Going further, Stephen Glazier in Random House's Word Menu defines plagiarism as "appropriation and publication of another's writing without consent" (409). He also defines it as "literary theft; stealing another's work without giving credit, passing it off as one's own (543). To summarize, plagiarism means taking someone else's words, ideas, or specialized information and passing them off as one's own; it is intellectual theft.
What irony that you would use someone else's description of plagiarism without giving them credit!