bock -
A strong dark beer brewed in the fall and aged through the winter for spring consumption.
Wikipedia
Bock is the term for a strong malty lager beer of German origin. Several substyles are based on bock, including maibock or helles bock, a paler, more hopped version generally made for consumption at spring festivals; dopplebock, a stronger and maltier version; and eisbock, a much stronger version made by partially freezing the beer and removing the water ice that forms. Originally a dark beer, a modern bock can range from light copper to brown in color.
