Hedonism was the belief that one should strive for pleasure above all else.
In 2267, Leonard McCoy described the society on Argelius II as completely hedonistic. When Captain James T. Kirk commented on how they "think very highly of their pleasure," Doctor Leonard McCoy rebuffed, "that's an understatement if I ever heard one." (TOS: "Wolf in the Fold")
In 2372, Quark questioned why Bajorans felt the need to have a time of cleansing, as they were not known for being "a bunch of hedonistic holosuite-obsessed drunkards to begin with." (DS9: "Bar Association")