Plagiarism is defined as appropriating someone else's words or ideas without acknowledgment.
Citation: Plagiarism. (2001). In Encyclopedia of Ethics.
Plagiarism is the intentional use of the ideas, words, or work of another without attribution, when the information they provide is not common knowledge, either in content or form. Plagiarism includes, but is not limited to, (1) quoting from the published or unpublished work of another without appropriate attribution; (2) paraphrasing or summarizing in one’s own work any portion of the published or unpublished materials of another without attribution;and (3) borrowing from another’s work information which is not in the domain of common knowledge.
Complicity is the intentional giving of assistance or the attempt to give assistance to another for the purpose of perpetrating academic dishonesty.
It happens more than you may think. Plagiarism over time:
According to the International Center for Academic Integrity 2020 study: https://academicintegrity.org/resources/facts-and-statistics
Kerkvliet, J., & Sigmund, C. L. (1999). Can we control cheating in the classroom? Journal of Economic Education, 30(4), 331-351.
Ashworth, P., Bannister, P., & Thorne, P. (1997). "Guilty in whose eyes? University students' perceptions of cheating and plagiarism in academic work and assessment." Studies in Higher Education, 22(2), 187-203. (EJ 549 250)
from the November 22, 1999 issue of U.S. News and World Report
from The Center for Academic Integrity (http://www.academicintegrity.org/)
McCabe, D. L., & Trevino, L. K. (1996). "What we know about cheating in college: Longitudinal trends and recent developments." Change, 28(1), 28-33. (EJ 520 088)
Above material from Plagiarism.org: http://www.plagiarism.org