1 [definition]
A mining process by which coins are distributed unevenly or unfairly, usually by a large portion of the maximum supply being mined during the launch of the cryptocurrency. Sometimes this is a result of mining difficulty not readjusting as predicted and miners being able to find blocks and gain block rewards much faster than expected.

1.1 Example

Dash (DASH) underwent an instamine at launch for the first 48 hours. Due to an issue with readjusting difficulty, about 10% of the total supply of Dash was mined within the first 2 days.