College is a postsecondary school or, sometimes, a component of a postsecondary institution.
Quebec[]
Quebec colleges are tasked with both pre-university and vocational education. (RIS Bouteina: "We're All In This Together")
Historically, colleges were strike-prone and led all student strikes in Quebec since 1967, including the 2012 Quebec student strike, which saw dozens of colleges on strike to protest a $1,625 tuition hike enacted by Jean Charest. (Star Trek: The Stoneship Files: "Rode the 300", "The Defector (TSF)")
Elsewhere[]
Some universities, like Bradbury University, referred to collections of departments teaching related fields of study as colleges. (Star Trek: Pendragon)
Lyran higher education was split between colleges and universities. A college primarily delivered undergraduate education, although some colleges, like Kinda Sorta College, offered graduate programs.
College counselors were often relied upon to help high school students with the process of getting into college (or university). (Star Trek: The Stoneship Files: "Educational Armageddon")
College fairs were organized by schools (and, in the Lyran case, each school was mandated by the government to have one college fair a year, or to have transportation provided to one on a yearly basis) to help students choose educational opportunities. (Star Trek: The Stoneship Files: "Post-Apocalyptic Education")
One could get into college early by applying early action, which was not binding, and early decision, which was binding. (Star Trek: The Stoneship Files: "Express Delivery")
College was considered by some Federation races as a rite of passage among the intellectual, and both Federation and Lyran colleges seemed to be mired in an arms race mentality. (Star Trek: The Stoneship Files: "Tax Crunch")