Rated load of a transformer
The rated load is the value of load resistance that will draw the rated transformer current at the rated transformer voltage.  For example, a line transformer that has a primary voltage of 120 VAC and a secondary voltage of 24 VAC that is rated for 2 amperes of current has a rated load of 24/2 ohms which is 12 ohms.  Thus if a 12 ohm resistor is placed across the secondary of this transformer, it will draw 2 amperes, the rated current of the transformer.