Idealism was a philosophy that viewed things in a favorable and sometimes unrealistic light. One example of idealism in art was pastoral works. (VOY: "Fair Haven") One who was idealistically romantic could be said to be quixotic. (PIC: "Broken Pieces")
According to Azetbur, her father Gorkon was seen as an idealist, in regards to his hope for peace between the Klingon Empire and the Federation. She believed that were it not for Praxis's explosion, his idealism would not have become reality. (Star Trek VI: The Undiscovered Country)
In 2375, Kyril Finn described Beverly Crusher as an idealist; she then commented that she lived in an ideal culture. (TNG: "The High Ground")
In 2373, Chakotay wondered how long the New Cooperative's ideals would last with the power to impose their collective will on others. (VOY: "Unity")
In 2375, Luther Sloan described Julian Bashir as a misguided idealist. (DS9: "Extreme Measures")