A refugee is an individual who has been displaced from his or her home who has sought shelter or a new home through the generosity of others such as the United Federation of Planets.
Many groups and/or species throughout the galaxy became refugees after their world was destroyed, made uninhabitable or usurped by another power. Some refugee species or groups include the Bajorans, select Humans (for example, the Maquis), the Skrreea and the El-Aurians. (TNG: "Ensign Ro", et al.; DS9: "Sanctuary", et al.; Star Trek Generations)