the.com/cocktail hour

means The informal, pre-dinner stretch of time—usually early evening—set aside for a drink and unwinding, often socially.

from The deeper origin of 'cocktail' itself is murky and debated (theories involve dock tails, cock feathers in mixed-breed horses, egg cups called 'coquetiers,' and more—none confirmed), but by the 1800s 'cocktail' meant a mixed spirited drink in American usage. 'Cocktail hour' followed as a 20th-century social custom, gaining particular traction during and after Prohibition, when drinking moved into private homes and needed its own ritualized time slot—often just before dinner.