1 [definition]
The mining of a certain number of coins prior to the cryptocurrency being made available to the public. This is generally done by developers prior to the source code being released to the public allowing anyone to mine.

1.1 Example

Ethereum (ETH) was pre-mined for a time before going public.

1.2 Example

Coins issued through an ICO are generally not pre-mined, rather they are simply created and distributed through a smart contract.