definition of plagiarism?

"Plagerism" is when you steal work or ideas from a person.

When you steal work or ideas from a lot of people, that's called "research."

Plagiarism is the practice of claiming or implying original authorship of (or incorporating material from) someone else's written or creative work, in whole or in part, into one's own without adequate acknowledgement. Unlike cases of forgery, in which the authenticity of the writing, document, or some other kind of object itself is in question, plagiarism is concerned with the issue of false attribution.

http://en.wikipedia.org/wiki/Plagiarism

Plagiarism

The unauthorized use or close imitation of the language and thoughts of another author and the representation of them as one's own original work.

http://www.dictionary.com/ -- a dictionary on the Internet