An exclusive privilege granted to an inventor to make, use or sale an invention for a set number of years (eg. in Canada, 17 years).
Normally, no one company can retain a monopoly over a product or service because this is considered to economically harmful to society.
But as a financial incentive to potential inventors, the state grants a temporary monopoly to that inventor through the issuance of a patent.
A person who is the registered owner of a patent can be referred to as a patentee.
In the US, patent law is set out in the US Code, Title 35. At Chapter 10, ¶101 thereof:
"Whoever invents or discovers any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof, may obtain a patent therefor, subject to the conditions and requirements of this title."
See also the article on Patents under Intellectual Property in Legal Resources.