Green’s Dictionary of Slang

a large glass; a full glass.

1567		Trial of Treasure Aiii: Hey rowse, fill all the pottes in the house.
1618		J. Taylor ‘Taylors Penniless Pilgrimage’ in Works (1869) I 138: Two or three good rouses of sherry.
c.1620		J. Hall Discovery of New World Bk 1 84: Gone is my flesh, yet thirst lies in the bone, Give me one rouse, my friend, and get thee gone.
1840		Tennyson Vision of Sin n.p.: Fill the cup and fill the can, Have a rouse before the morn [F&H].