A hogshead is a large cask of liquid (less often, of a food commodity). More specifically, it refers to a specified volume, measured in Imperial units, primarily applied to alcoholic beverages such as wine, ale, or cider.
A tobacco hogshead was used in American colonial times to transport and store tobacco. It was a very large wooden barrel. A standardized hogshead measured 48 inches (1220 mm) long and 30 inches (760 mm) in diameter at the head (at least 550 L, depending on the width in the middle), Fully packed with tobacco, it weighed about 1000 pounds (450 kg).
The Oxford English Dictionary (OED) notes that the hogshead was first standardized by an act of Parliament in 1423, though the standards continued to vary by locality and content. For example, the OED cites an 1897 edition of Whitaker's Almanack, which specified the number of gallons of wine in a hogshead varying by type of wine: claret 46 (presumably imperial) gallons, port 57, sherry 54; and Madeira 46. (209, 259, 245, and 209 L) The American Heritage Dictionary claims that a hogshead can consist of anything from 62.5 to 140 (presumably U.S.) gallons (235-530 L).
Eventually, a hogshead of wine came to be 63 wine/US gallons or 52.5 imperial gallons (both ~238.5 L), while a hogshead of beer or ale is 54 gallons (250 L if old beer/ale gallons, 245 L if imperial).
A hogshead was also used as unit of measurement for sugar in Louisiana for most of the 19th century. Plantations were listed in sugar schedules as having produced x number of hogsheads of sugar or molasses.