If it is not the feminine of mocker, it may be an error by burrower ("burring machine"), or perhaps by Bullader.
It means that he mocks, that he mocks. That evades or avoids. That deceives or confuses.
MOCKER who mocks, who evades. 2 . That mocks someone or something. Not to be confused with BURLADERO, Shelter panel for bullfighters and picadores that exists in the bullrings next to the arena and in front of the stands