(1) A strategy involving the simultaneous purchase and sale of options of the same class and expiration date but different strike prices. In a bull vertical spread, the purchased option has a higher delta than the option that is sold. For example, in a call bull spread, the purchased option has a lower exercise price than the sold option. Also called Bull Vertical Spread. (2) The simultaneous purchase and sale of two futures contracts in the same or related commodities with the intention of profiting from a rise in prices but at the same time limiting the potential loss if this expectation is wrong. In agricultural commodities, this is accomplished by buying the nearby delivery and selling the deferred.
Source: Commodity Futures Trading Commission