- Old English Sæterdæg, Sæternesdæg, literally "day of the planet Saturn," from Sæternes (genitive of Sætern; see Saturn) + Old English dæg "day." Partial loan-translation of Latin Saturni dies "Saturn's day" (cf. Dutch zaterdag, Old Frisian saterdi, Middle Low German satersdach; Irish dia Sathuirn, Welsh dydd Sadwrn). The Latin word is itself a loan-translation of Greek kronou hemera, literally "the day of Cronus."
Unlike other day names, no god substitution seems to have been attempted, perhaps because the northern European pantheon lacks a clear corresponding figure to Roman Saturn. An ancient Nordic custom, however, seems to be preserved in Old Norse laugardagr, Danish lørdag, Swedish lördag "Saturday," literally "bath day" (cf. Old Norse laug "bath"). German Samstag (Old High German sambaztag) appears to be from a Greek *sambaton, a nasalized colloquial form of sabbaton "sabbath," also attested in Old Church Slavonic sabota, Russian subbota, French samedi.
Saturday night has been famous for "drunkenness and looseness in relations between the young men and young women" since at least mid-19c. Saturday-night special "cheap, low-caliber handgun" is American English, attested from 1976 (earlier Saturday-night pistol, 1929).