Plagiarism

According to Plagiarism.org, to "plagiarize" means:

• to steal and pass off (the ideas or words of another) as one's own

• to use (another's production) without crediting the source

• to commit literary theft

• to present as new and original an idea or product derived from an existing source

In other words, plagiarism is an act of fraud. It involves both stealing someone else's work and lying about it afterward.