A troll was a mythical being with supernatural powers found in the mythology of various cultures, including Earth. Some would apply the term to others who were being particularly offensive with their words or actions.
In 2366, Lwaxana Troi called DaiMon Tog "a toad-faced troll" during that year's Trade Agreements Conference after his repeated advances towards her and an offer to purchase her. (TNG: "Ménage à Troi")
In 2369, Q called Quark a "repulsive little troll" after making him disappear when he attempted to meet Vash in her quarters. (DS9: "Q-Less")
The following year, Kira Nerys referred to the Ferengi as trolls during a discussion with Jadzia Dax. (DS9: "Rules of Acquisition")
That same year, Kira referred to Quark as "the little troll who runs the dabo tables when speaking to Vedek Bareil Antos. (DS9: "Shadowplay")