dram
1811 Vulgar Tongue
A glass or small measure of any spirituous liquors, which, being originally sold by apothecaries, were estimated by drams, ounces, &c.
Wikipedia
To correspond with the dram definition from the Vulgar Tongue, Wikipedia has it listed as: “Dram is also used informally to mean a small amount of liquid, especially Scotch whisky.”
Merriam-Webster
A small portion of something to drink : a small amount
