Definitions:

1. A genus of Gram-positive, rod-shaped bacteria in the family Bacillaceae, found in various environments including soil, air, and water. NOUN
   • The genus Bacillus includes bacteria that can survive extreme conditions by forming endospores.
2. A term used in microbiology to describe a type of bacteria that is rod-shaped. NOUN
   • Scientists often study Bacillus subtilis as a model organism for understanding bacterial cell processes.
3. A variety of bacterium. NOUN
   • Bacillus firmus is a bacillum bacterium that is used in the production of biofuels.
4. Any of various rod-shaped, spore forming aerobic bacteria in the genus Bacillus, some of which cause disease. NOUN
   • Bacillus anthracis is the bacterium responsible for causing the serious disease anthrax.
5. Refers to bacteria within the genus Bacillus, which is a large genus of Gram-positive bacteria. NOUN
   • Bacillus cereus is the bacillus bacterium that can cause food poisoning in humans.

Synonyms:

• bacterium
• germ
• microbe
• microorganism
• pathogen