PH's explanation is what most people mean by this adjective. There are winemaking techniques that seem to add to this:
First, low yields in the vineyard generally assure more uniform and optimal ripening, thus increasing concentration - to be "extracted" during wine making.
Some winemakers put must through a pre-fermentation cold-soak, allowing the juice to macerate with the skins, stems (if stems included) and grape solids. That which is extracted at cooler temperatures - temperatures too low for fermentation to begin - tends to be colors, aromatic components and just plain flavor. This is especially common in fine Pinot Noir.
Some winemakers will bleed off some free run juice - saignee - to increase the juice to skin ratio in the fermentation vessel, potentially making for a darker, more "extracted" wine. This may also yield some rose', depending on the time the juice and skin were in contact.
Small fermentation vessels tend to create this high juice to skin ratio as well.
Barrelling wines down dirty, with gross lees and grape solids in the juice continues the extraction process slowly as the wine ages in barrel. Careful racking of the wine off the remaining lees is essential to getting a clear wine, which I personally think is essential.
An extended post-fermentation maceration on the skins seems to aid in the formation of nice, long chain tannins and assists in the development of numerous phenolic compounds, as well.
Lastly, careful racking, coupled with microbiologically stable juice and negligible RS can allow a winemaker to bottle a wine without fining or filtering - which will preserve pigment and benign solids.
There are many other things a winery does both in the vineyard and in the cellar to make a wine "extracted," but this is some of the major stuff.
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