deep-sinkern.Australianslang(a) a drinking-glass of the largest size, so called from a fanciful resemblance to a deep mineshaft;(b) the drink served in such a glass.
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1886 F. CowanAustralia 32Long-sleever, Bishop Barker, and Deep-sinker, synonyms of Yankee Schooner.
1897 Argus (Melbourne) 15 Jan. 6/5 in E. E. Morris Austral Eng. (1898) A tumbler—whether medium, small, or deep-sinker.