Ah, yes, possibly a currency conversion fee.
My card gives a good conversion rate and does not charge a conversion fee, a fact that I've often used to my advantage. For example, a few years ago my wife went on a multi week hiking expedition and the site that we booked it through was an international site. They said that we could pay in any currency that we wanted, so we converted the charge for each currency to USD and found that paying in GBP was significantly cheaper than paying in USD, so we paid with that.
