In calculating a spot or future price between two currencies, reference to their respective quotations in a third currency determines the cross rate.
Definition 2.
Cross rate is an exchange rate between two currencies derived by dividing each currency’s exchange rate with a third currency.
For example, if ¥/$ is 140 and DM/$ is 1.5000, the cross rate between ¥ and DM is ¥140/$ 4 DM1.5000= ¥93.3333/DM.