'groggy' originates from English, specifically the nautical slang word 'grog', where 'grog' referred to diluted rum issued to sailors (named after Admiral 'Edward Vernon', nicknamed 'Old Grog').

'grog' (18th cent.)—named after Admiral 'Old Grog' (from his grogram cloak)—gave rise to the adjective 'groggy' meaning 'affected by grog'; over time the sense broadened to mean 'dazed or weak'.

Initially, it meant 'affected by grog (rum)', but over time it evolved into its current meaning of 'dizzy, weak, or dazed'.