solera (səˈlɛərə), noun
A system for aging sherry, other alcoholic beverages, or vinegar, by mixing different ages of the beverage to produce a consistently-aged blend.
Etymology: Spanish solera, bottom, base.
I ran across the word in this
local news article. "In one room, 16 French oak barrels had been stacked in four vertical columns to make a solera."
The picture is from the
WIkipedia article.