ˈPeter ˌprinciple, the BrE AmE noun [singular] especially humorous
the idea that each person who works in an organization gradually moves up to higher and higher levels, until they reach their own ‘level of incompetence’ (=the level at which they are no longer able to do their job well). They then remain at this level for the rest of their working life, and this has a bad effect on their own work and on their organization. The idea was invented by the Canadian writer and teacher Laurence Peter.