Oak The traditional timber from which casks are made. Bourbon casks are made from American white oak, sherry butts from European oak.
Octave See "Casks".
Operational Distillery A distillery which is working and producing spirit or in its silent season. Although such a distillery is maturing the spirit it has produced, it may not have been producing for a sufficient number of years in its present form to be making its whisky available for wholesale or retail.
Organic Whisky Following the current popular trends in food and drink, this is whisky made from barley grown in ground free from inorganic fertilizers and treated with non-chemical pesticides.
Original Gravity Refers to the specific gravity of the wort from which the final spirit is derived.