What does firkin mean in cooking?

firkin means: A chuck wagon’s sourdough container; also a dough keg. (in Cooking Dictionary)

What else does firkin mean?

• Small wooden vessel or barrel. (in Merlin Dictionary)
• One of many British units of capability, often equal to or close to ¹ / ₄ A barrel, 9 gallons or 34 liters. (in Merlin Dictionary)