Disposal container with locking closure

A lid for covering an interior of a medical waste receptacle base. The lid includes a cover having a generally circular opening. The opening including an upper rim surrounding an upper central axis and a lower rim surrounding a lower central axis that is non-co-linear with the upper central axis. The lid includes a generally circular closure sized for blocking the opening. The lid includes a guide extending along the cover. In the open position, the closure is at least partially out of alignment with the opening. In the closed position, a center axis of the closure is aligned with the upper central axis to block the opening. The closure is moveable from the closed position to a locked position in which the center axis of the closure is coincident with the lower central axis.