king-size

1. extra large; as, a king-size bed.
2. Of or pertaining to a king-size bed; suitable for a king-size bed; as, a king-size bedcover.

A king-size bed is the largest size generally sold commercially; it is larger than a queen-size, which in turn is larger than a full-size (or double) bed, and that in turn is larger than a twin-size (or single) bed. The mattress for a king-size bed is typically about 76 inches wide and 80 inches long.