courier:
(plural: ‘couriers‘; pronunciation: the letter ‘c’ is said with a ‘k’ sound — for the right pronunciation of this word, please click here)

a courier delivering a packet to a client
a person (messenger) who carries and gives urgent and important messages quickly and safely from one person or place to another by travelling fast; a messenger;
a tour guide working for a travel agency;
a high-level government officer (diplomat) who carries important messages or correspondence (letters, documents, etc.) from one’s country to another;
a spy (secret agent) who carries secret messages from the enemy country to his/her own country;
a personal attendant whose job is to make travel arrangements for rich people,

two couriers (spies) passing on secret messages through mobile phones
After dropping out of high school, young Milton took up a job as a local courier to support his ailing mother.
Most couriers in crowded cities use bicycles to go from place to place because when are get caught in a traffic jam, they don’t have to wait for it to clear; they can just walk on the pavement/sidewalk with their bicycle and once there are out of the traffic jam they can ride along fast.
Like most other manual jobs, couriers and courier services also have lost some of their business to the latest technological developments, like for example, most of the business transactions and documents are sent from one office to another on via emails so that actual paper document is not needed to be sent by a courier or courier service.

DHL — one of the most efficient international couriers
