From the weekday name, ultimately from Tiw's day, honoring the Norse god Tyr.
Tuesday is among the most striking of English word-names, carrying both cosmic mythology and everyday familiarity. The word derives from Old English Tiwesdæg, "the day of Tiw," named for the Norse and Germanic god Tyr — a one-handed deity of law, justice, and heroic glory, who sacrificed his hand to bind the great wolf Fenrir and protect the gods. The day-naming convention itself was a Roman import adapted to Germanic mythology: the Romans named their days after planets and gods (dies Martis, Mars's day, for Tuesday), and Germanic peoples substituted their equivalent deity, Tyr, for Mars.
As a given name, Tuesday is famously associated with Tuesday Weld, the American actress born Susan Ker Weld, who adopted the nickname in childhood and carried it through a career spanning Hollywood films of the 1960s and 70s. Her beauty, unconventionality, and distinctive name made Tuesday feel glamorous and slightly otherworldly — a name that signaled someone who operated on their own terms. That association has never fully faded.
Using days of the week as names is an old practice in some West African traditions, where children are named for the day of their birth — a custom that lends Tuesday new cross-cultural depth. In contemporary usage, Tuesday appeals to parents drawn to word-names with history: not invented, not merely decorative, but a word used billions of times that, once applied to a person, suddenly sounds entirely fresh and singular.