Definition of "bacillus" [ba•cil•lus]

• Any of various rod-shaped, spore-forming, aerobic bacteria of the genus Bacillus that often occur in chains and include B. anthracis, the causative agent of anthrax. (noun)
• Any of various bacteria, especially a rod-shaped bacterium. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "For instance, the germ that causes typhoid fever is called the _bacillus typhosus_; that which causes tuberculosis is called the bacillus tuberculosis; while the germ of diphtheria known as the _Klebs-Loeffler bacillus_, after the two men who discovered it."
• "Which disease caused by a bacillus is abbreviated as "TB"?"
• "He finally concluded that the only remaining competitor for the distinction of causing the pestilence was a germ which he called bacillus x."