Self-plagiarism: re-using one's own work without properly citing/acknowledging previous use.
Stephen Gilliver. Forgive me for repeating myself: Self-plagiarism in the medical literature. European Medical Writers Association 2012; 21(2): 150-3. Adapting from: Miguel Roig. Avoiding plagiarism, self-plagiarism, and other questionable writing practices: a guide to ethical writing. http://ori.hhs.gov/sites/default/files/plagiarism.pdf