To add to "Dave"'s response, "monitor" often meaning a small, revealing, heavy-duty speaker that will fit into tight spaces or on top of a mixing board, usually used very near-field. Today's powered keyboard speakers that sit on top of a keyboard would sort of fit the original bill..
Weren't the old 70's Roger's cylindrical speakers designed this way to fit into a mobile recording unit, in a van?
Weren't the old 70's Roger's cylindrical speakers designed this way to fit into a mobile recording unit, in a van?