A peg is a unit of volume, typically used to measure amounts of liquor in the Indian subcontinent. Equal to 30 mL, the terms "large peg" and "small peg" are also used, equal to 60 mL and 30 mL, respectively, with "peg" alone simply referring to a small peg. The unit is most likely derived from the imperial fluid ounce (approximately 28.4 mL) during the time of the British Raj, and presumably for the sake of convenience was later standardised to 30 mL. Informally, a peg is also understood to be a single shot of any alcoholic drink.
Popular belief suggests that during the time of the British Raj, mine owners would give a drink to miners at the end of their shift to get some relief from the cold working conditions. Workers would eagerly look forward to it, calling it a "precious evening glass", which was subsequently abbreviated simply to "peg".