A Guild Transport is a large, oval-shapped starship used by the Spacing Guild to transport passengers across the Universe in Dune. They are much smaller when compared to the Guild Heighliner, and fit into the Heighliner by connecting with docking ports that fit the shape of the Transport.
House Atreides used a fleet of these ships to transport Caladan's entire population to Arrakis. The entire fleet fit inside the Heighliner.