Definition of "toper"

A Toper this! He plied his glass / More strictly than he said the Mass, […]

1818, John Keats, On Some Skulls in Beauly Abbey, near Inverness

The liquor soon mounted into their heads, as it generally does even with the arrantest topers newly landed from sea, and they began capering about most obstreperously.

1851 November 14, Herman Melville, “The Spouter-Inn”, in Moby-Dick; or, The Whale, 1st American edition, New York, N.Y.: Harper & Brothers; London: Richard Bentley, page 16

[…] Mrs. Irons rebelled in her bed, and refused peremptorily to get up again, to furnish the musical topers with rum and lemons. […]

1863, J[oseph] Sheridan Le Fanu, “Narrating How Lieutenant Puddock and Captain Devereux Brewed a Bowl of Punch, and How They Sang and Discoursed Together”, in The House by the Church-yard. […], volume I, London: Tinsley, Brothers, […], page 304

“Well, if you ask me, Barney is a combination of eight ball, mick, and shonicker,” said McArdle, one of the corner topers.

1932, James T. Farrell, chapter 6, in Young Lonigan, section 3, page 156