To TOST, or Toast,
to name or begin a new Health. Who tosts now? Who Christens the Health? An old Tost; A pert, pleasant, old Fellow.
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Entry taken from 1736 Canting Dictionary, by Nathan Bailey.
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The Vulgar Tongue originally collected by Grose, 1811.
Also see examples in Canting Songs and Slang Rhymes collected by John S. Farmer (1896).