TCA, short for 2,4,6-trichloroanisole, refers to a wine fault that originates in cork, or cork taint. bottles with cork taint are referred to as ‘corked.’ while harmless to people, mere nanograms of TCA leaves bottles only shadows of their former juice, often flat, without fruit, expressing alcohol and acid in place of flavor. in higher concentrations, it's vaguely reminiscent of wet cardboard, old newspaper, or wet dog.
TCA doesn't indicate anything wrong with the cuvee, the winery, or the vineyard; it's just the particular bottle that happened to have a bad cork. some producers use cork alternatives to avoid the flaw altogether.
everyone has different thresholds for perceiving TCA, but TCA becomes more apparent the longer the bottle is open. if you couldn’t sense the TCA in a bottle you think is corked on your first try, keep smelling and tasting to familiarize yourself with this unfortunate flaw. if the wine gets better, rejoice! It wasn’t corked in the first place.