油桶 (yóu tǒng) literally combines 油 (yóu), meaning 'oil', and 桶 (tǒng), meaning 'drum' or 'barrel'. It refers specifically to a standardized metal or plastic container used for storing and transporting liquids—most commonly petroleum-based oils, fuel, lubricants, or industrial chemicals. These drums are typically cylindrical, sealed with a removable lid, and often hold 200 liters (about 55 gallons) in China and many other countries.

The term is widely used in logistics, manufacturing, construction, and automotive repair settings. While it originally referred only to oil, 油桶 is now used generically for any large drum-shaped container—even when holding non-oil substances like paint or cleaning agents—especially in informal or workplace speech. It carries no emotional connotation and is neutral in register, suitable for both technical documentation and everyday conversation.