A misfit was someone who did not share many qualities with other members of a group they belonged to.
Terkim was the misfit of Guinan's family. (TNG: "Hollow Pursuits")
J'naii like Soren were called misfits and deviants and criminals. (TNG: "The Outcast")
B'Elanna Torres described herself as being a lost and hostile misfit in her own eyes, but not Kathryn Janeway's. (VOY: "Coda")
Genetically engineered Humans were sometimes called misfits. (DS9: "Inquisition", "Chrysalis")
Mortimer Harren asked if Captain Janeway felt responsible for having three misfits aboard USS Voyager, namely himself, Tal Celes, and William Telfer. (VOY: "Good Shepherd")