A broad definition of patent is that a patent is a license that protects your intellectual property by assigning you exclusive rights to use that property.
The Canadian Intellectual Property Office (CIPO) offers a more specific definition of patent: "A patent is a right, granted by government, to exclude others from making, using, or selling your invention in Canada.".
The 'in Canada' part of the definition of patent is important because when you patent a invention, your patent only grants you rights protection in that particular place. So if you want to guard your exclusive right to use your invention in North America, you will have to get separate patents in Canada, the United States and Mexico. See Applying for a Patent Outside Canada (CIPO).
I would also add the phrase "for a specific time period" to the definition of patent. In Canada and Mexico, patent protection lasts for 20 years from the date of filing. In the United States, plant and utility patents are granted for 20 years, while design patents last 14 years. (Note that the 20 year period is not automatic; you need to pay maintenance fees on your patent to keep it in force.)
"Patents cover new inventions (process, machine, manufacture, composition of matter), or any new and useful improvement of an existing invention" (CIPO).
If you are interested in applying for a patent, you also need to be aware of two things:
- Only the legal owner of an invention can apply for a patent. So if the inventor makes the invention as part of an employment contract, the employer may own the invention and have the right to the patent.
- Not all inventions qualify for patent protection. In the words of the Canadian Intellectual Property Office, patents are only granted for products or processes that are novel, useful, and inventive.
For information on how to get a patent, see How to Get a Patent in Canada.