plugin
In MariaDB 5.1 and earlier, a separately installable form of the InnoDB storage engine that includes features and performance enhancements not included in the built-in InnoDB for those releases.
For MariaDB 5.5 and higher, the MariaDB distribution includes the very latest InnoDB features and performance enhancements, known as InnoDB 1.1, and there is no longer a separate InnoDB Plugin.
This distinction is important mainly in MariaDB 5.1, where a feature or bug fix might apply to the InnoDB Plugin but not the built-in InnoDB, or vice versa.
See also built-in.
See also InnoDB.