Commodities were goods which could be traded in a standardized form and large quantities, with little difference in quality regardless of origin.
In 2371, Doctor Renhol feared that Trill symbionts would become commodities, easily purchased or fought over, if it became known that almost half of all Trill were eligible to become joined with symbionts. (DS9: "Equilibrium")
According to Kai Winn later that year, boton, moreka and salam grass all were valuable commodities for export from Bajor. (DS9: "Shakaar")
According to Neelix in 2374, protomatter was one of the most-sought commodities in the Delta Quadrant since it was the best available energy source. (VOY: "Mortal Coil")
In 2375, Thadial Bokar used the guise of a commodities broker while working for the Orion Syndicate. (DS9: "Prodigal Daughter")
According to Neelix in 2376, he discovered that "honesty, loyalty, hard work" were commodities he possessed in abundance after joining the crew of the USS Voyager. (VOY: "Live Fast and Prosper")