both refer to movie chains (i.e., Loews, AMC Theatres) with movie theatres that screen more than one film at a time, as opposed to single-screen theatres. A multiplex has from 2 up to 16 screens, a megaplex has 16 or more screens; plex is the abbreviation for a multiplex theatre.
A morula (Latin, morus: mulberry) is an early stage embryo consisting of cells (called blastomeres) in a solid ball contained within the zona pellucida.
Radula definition, a chitinous band in the mouth of most mollusks, set with numerous, minute, horny teeth and drawn backward and forward over the floor of the mouth in the process of breaking up food. All the mollusca, except the bivalves, are provided with this radula.