Nouns

(n)plagiarist, plagiarizer, plagiariser, literary pirate, piratesomeone who uses another person's words or ideas as if they were their own
(n)pirate, buccaneer, sea robber, sea roversomeone who robs at sea or plunders the land from the sea without having a commission from any sovereign nation
(n)pirate, pirate shipa ship that is manned by pirates

Verbs

(v)piratecopy illegally; of published material
(v)commandeer, hijack, highjack, piratetake arbitrarily or by force“The Cubans commandeered the plane and flew it to Miami”