O.I.V. Office International de la Vigne et du Vin (International Bureau of Grapevines and Wine) An intergovernmental agency that addresses technical, scientific and economic issues related to grapevine cultivation and wine production.
O.N.I.VINS Office National Interprofessionnel des Vins; a French government organization that serves as a link to the wine production sector with the goal of guiding and standardizing the French wine industry in a European and international context.
ODOR Perceived directly by the nose, as opposed to flavors detected through the mouth, there are a wide variety of odors that can appear in wine, including everything from fruits and flowers to spices, herbs, and roasted or gamy notes.
OENOLOGY The science of wine and the physical, biological and chemical processes of its production and aging, as well as the agronomic principles behind its cultivation.
OFF-DRY A term used to describe white wines that contain some residual sugar, but much less than sweet wines.
OIDIUM Also known as powdery mildew, this disease appears as a grayish tint on the leaves and fruit and dehydrates the grapes. Can be treated with sulphur.
OPEN Said of a wine that is ready to drink, in which the aromas have been released.
ORGANOLEPTIC Refers to the qualities or properties of a wine perceived by the senses, such as color, aromas and flavors.
OXIDATION The result of contact between wine and the oxygen in air. Oxidation is undesirable in white wines as it denatures their aromatic components before fermentation. When it is excessive, it changes the color of the wine, introducing orange hues in red wines and brown hues in white wines, as well as the bouquet, adding rancid notes of wax polish and Madeira. However, oxidation is desirable in the production of Vins Doux Naturels and imparts sought-after aromas of hazelnut, nuts and fruit preserves.