In ancient Greek, the root word galact- (from γάλα/γάλακτος) means milk. While "Galacta" is not a proper term in ancient texts, it is the root for Galaxias (the Milky Way). It is also closely tied to mythological figures like Galatea ("she who is milk-white").
The Milky Way (Galaxias Kyklos)
To the ancient Greeks, the glowing band of the Milky Way across the night sky was known as Galaxias Kyklos, meaning the "milky circle".
The Myth of Hera: The most famous story involves Zeus tricking his wife, the goddess Hera, into nursing his infant mortal son, Heracles. When Hera awoke and realized she was nursing a baby that was not hers, she pushed the infant away. The spurting breast milk sprayed across the heavens, creating the Milky Way. [4, 6]
Galatea ("She who is milk-white")
While not spelled "Galacta," this closely related name features prominently in ancient Greek mythology:
The Sea Nymph: In the works of Homer and Hesiod, she is a beautiful Nereid (sea-nymph) beloved by the Cyclops Polyphemus.
The Living Statue: In Ovid's Metamorphoses, it is the name given to an ivory statue of a woman carved by the sculptor Pygmalion. Because he fell so deeply in love with his own creation, the goddess Aphrodite took pity on him and brought the statue to life. [3, 7, 8, 9]
Real-World Historical Region (Galatia)
If you are thinking of a real geographical region, you may be referring to Galatia.