The smallest price change that a given exchange rate can make. Since most major currency pairs are priced to four decimal places, the smallest change is that of the last decimal point - for most pairs this is the equivalent of 1/100 of one percent, or one basis point.
Investopedia Says: For example, the smallest move the USD/CAD currency pair can make is $0.0001, or one basis point. The smallest move in a currency does not always need to be equal to one basis point, but this is generally the case with most currency pairs.
The spread between the bid and ask varies among FCM's and brokers. Depending on your trading volume you can get better (tighter) spreads if you request based on your trade size and frequency. The actual spread is the cost of doing business and providing you the service to trade online. So you can call this the equivalent of the brokers commission.