Firmus is the name of several early Christians, of whom we particularize: (1) A martyr with Rusticus at Verona, A.D. 304; commemorated August 9. (2) Bishop of the Cappadocian Caesarea, deposed by the Oriental party, and died A.D. 439. He left a number of letters, first published by Muratori, Anecdot. Graec. (Patav. 1707), also by Migne, Patrol. lxxvii, 1477. See Smith, Dict. of Christ. Biog. s.v.