1. Wine that has lost its carbonation or effervescence, becoming dull and lifeless in taste
This sparkling wine has gone flat because the bottle was left open.
Este vinho espumante ficou sem gás porque a garrafa foi deixada aberta.
2. Wine lacking in flavor, complexity, or vibrancy on the palate
The wine tasted flat and uninspiring after sitting in the glass for too long.
O vinho tinha um gosto insosso e desinspirador depois de ficar no copo por muito tempo.