Gaillac, a town of France, in the department of Tarn, on the right bank of the river Tarn, an affluent of the Garonne, 12 m. W. by-S. of Albi; pop. in 1866, 7,870. It is in a fertile region, abounding in vineyards, and surrounded by suburbs, one of which contains a large square, but the streets are exceedingly narrow. It contains two old churches, a communal college, a military prison, and an agricultural society, and various industrial establishments. Gaillac produces white and red wines of superior quality, the latter celebrated for enduring long sea journeys.