The term UNIT ROLLER COASTER is composed of three words: 'UNIT, ' 'ROLLER, ' and 'COASTER.' The first word, 'UNIT, ' is a three-letter word meaning 'a single thing or person.' The second word, 'ROLLER, ' is a five-letter word meaning 'a cylindrical object that rotates on an axis.' The third word, 'COASTER, ' is a seven-letter word meaning 'a device used for amusement rides, typically in the form of a track with cars that move along it.' Together, these three words describe a type of amusement ride consisting of a track with cars that move along it, typically in a cylindrical shape.