From the English word 'tally' (count); also an Irish diminutive of Talulla meaning 'abundance'.
Tally carries the warm informality of a nickname that has grown confident enough to stand on its own. It most commonly derives from Tallulah, a name of Native American origin — borrowed from a Muscogee or Choctaw word meaning "leaping water" — though it also serves as a pet form of Natalia, the Latinate name rooted in the phrase "dies natalis," or birthday, particularly associated with Christmas Day births in the early Christian tradition.
There is an older thread as well: Talitha, the Aramaic word for "little girl," appears in the Gospel of Mark in the miracle story "Talitha cumi" ("Little girl, arise"), lending the name an unexpected scriptural depth. In cultural life, Tallulah Bankhead — the tempestuous, larger-than-life American actress of the 1930s and 40s — gave the root name a glamorous, slightly dangerous edge that Tally inherits in softer form. The standalone Tally gained fresh momentum in the early 2000s through Scott Westerfeld's dystopian YA novel *Uglies*, whose brave, conflicted protagonist Tally Youngblood introduced the name to a generation of readers. Today Tally sits comfortably in the space between nickname and proper name — breezy and unpretentious, yet with enough history behind it to feel grounded.