the.com/authorisation

means Official permission granted by someone with the power to grant it, usually accompanied by a signature, a stamp, or a code.

from Traces back through French to the Latin 'auctor' — an originator or guarantor, the same root that gives us 'author.' To authorize something is, at bottom, to make yourself its author: the person whose name backs the act. The British '-ise' spelling versus American '-ize' is just a later split in the family, not a difference in ancestry — both descend from the Greek verb-forming suffix '-izein' by way of Latin and French.