Plagiarism
Plagiarism: "to steal and pass off (the ideas or words of another) as one's own: use (another's production) without crediting the source: to commit literacy theft: present as new and original an idea or product derived from an existing source."
Purdue University prohibits "dishonesty in connection with any University activity" and plagiarism is an example of such dishonesty. The Office of the Dean of Students has developed a guide for students on academic integrity, which includes references to Purdue University's Regulations Governing Student Conduct. Citing your sources appropriately will help avoid plagiarism and protect you from any questions about the originality of your thoughts and ideas.
Plagiarism and copyright are not the same. You can give proper attribution and still be infringing on someone's copyright. Plagiarism is about providing credit for the work and copyright is about using only the amount of work that is necessary to make your point.