Argratha was an inhabited planet in the Gamma Quadrant. This was the homeworld of the humanoid Argrathi. The planet was governed by the Argrathi Authority. Instead of imprisoning criminals, their legal system punished offenders by imprinting the convicted with fabricated memories of incarceration.

In 2372, Miles O'Brien visited the planet. (DS9: "Hard Time")

This planet was only mentioned in dialogue.
"ar-GRATH-a" was the pronunciation for this planet's name from the script pronunciation guide.
According to Star Trek: Star Charts (p. 74), Argratha was located in the Argratha system. The primary was a G-class star. Argratha was a location visited by the Gamma Quadrant Bio-Survey (2369-75).