What is the best synonym for plagiarism -?

There isn't a single perfect synonym for plagiarism, as its meaning is quite nuanced. However, depending on the context, some good options include:

Formal:

* Theft (emphasizing the illegal aspect)

* Misappropriation (emphasizing the wrongful taking)

* Unauthorized copying (emphasizing the lack of permission)

* Literary theft (specifically for written works)

* Academic dishonesty (emphasizing the ethical violation)

* Fraud (when used to gain academic or professional advantage)

Informal:

* Copying (general term but often used in a negative context)

* Stealing (emphasizing the wrongfulness)

* Borrowing (when used in a deceptive way)

* Passing off (claiming someone else's work as your own)

The best synonym will depend on the specific situation and the intended message.