Rule or distribution of political power according to knowledge or competence, rather than by equal votes. The word means 'rule of the knowledgeable'.
In more detail
Philosophers trace the idea to Plato. Jason Brennan's Against Democracy (2016) defines a regime as epistocratic to the extent that power is formally distributed by competence, skill and good faith. Variants include restricted suffrage, plural voting, knowledge-weighted voting and an epistocratic veto. Critics, including David Estlund, deny that knowledge alone gives authority to rule.