Plagiarism is the act of taking another person's writing, conversation, song, or even idea and passing it off as your own. UC guidelines say:
Plagiarism − Form of cheating involving the dishonest presentation of work that has been produced by somebody else as if it is one's own.
Poor academic practice - An unintended breach of instructions, carelessness, neglect or similar, where there is no dishonest intent.
The attached document will help you make sure you are not inadvertently plagiarising someone else's work.
Hill, D. J. (2015). A beginners' guide to plagiarism. Wellington: Ako Aotearoa.