Consent, permission, or clearance (all interchangeable terms) given by a right-holder (the licensor) to someone (the licensee) to exercise a right held by the licensor. The licence can be oral or written. An exclusive licence gives the licensee alone the right of exercise, to the exclusion of even the licensor (this licence usually has to be written). A sole licence is the same, except the licensor can compete with the licensee. A non-exclusive licence allows the licensor to appoint other licensees in the same area to exercise the right.
A purely contractual relationship under which one party, the licensor, agrees to permit the other, the licensee, to use something (usually some form of intellectual property such as a patent, trade-mark, or copyright) in return for compensation (usually in the form of a payment based on sales revenues, referred to as a royalty).
Permission to be on the land of another.