What is an AC to DC converter called?

While 'rectifier' is the component which converts AC to DC, the entire converter unit which converts AC to DC is also known by the name 'Eliminator'.

This, as the old timers will tell you, is short for 'Battery Eliminator', as quite often, the AC-DC converter is used as a substitute for having to use the batteries. It allows the battery driven equipment to be powered from the mains directly.