Definition of bacillus Calmette-Guérin

bacillus Calmette-Guérin (buh-SIH-lus KAL-met-gay-RIN): A weakened form of the bacterium Mycobacterium bovis (bacillus Calmette-Guérin) that does not cause disease. Bacillus Calmette-Guérin is used in a solution to stimulate the immune system in the treatment of bladder cancer and as a vaccine to prevent tuberculosis. Also called BCG.