dionysium Save DMLBS dionysium [CLonly pl.] , festival in honour of Dionysus. b (transf.) devotion or guild of devotees. ~a, festa Bacchi Osb. Glouc. Deriv. 173. b isti sunt fratres et sorores ~orum S. Anselmi (MS BL Cotton Nero C IX f. 22) Med. & R. Stud. I 13n.