Crosses or Cross Pairs
"crosses" are basically pairs that do not include the USD. For example, the GBP/JPY and EUR/JPY are both popular crosses. It is called a cross because your are taking two pairs, for example the GBP/USD and the USD/JPY and crossing them to become the GBP/JPY.
Usually crosses carry a higher spread or commission from brokers because you are in essence paying for the spread twice.