The quote currency is the second currency listed in a forex pair. It is also known as the counter currency.
The price of a forex pair reflects how much it costs to purchase one unit of the base currency by selling the quote currency.
In a pair listed as GBP/USD, USD is the quote currency. In EUR/CHF, CHF is the quote currency. The first currency listed is referred to as the base currency; GBP and EUR would be the respective base currencies for the above examples.