What is Code ?
Code is (noun) 1. a set of laws or rules of behaviour The hotel has a strict dress code, and people wearing jeans are not allowed in. 2. secret words or a system agreed in advance for sending messages We’re trying to break the enemy’s code. He sent the message in code. 3. a system of numbers or letters which mean something The code for Heathrow Airport is LHR. What is the code for phoning Edinburgh?
source: Easier English, Student Dictionary Upper Intermediate Level