Bacillus

//bæˈsɪl.əs// noun

noun ·Uncommon ·Advanced level

Definitions

Noun
  1. 1
    Any of various rod-shaped, spore-forming aerobic bacteria in the genus Bacillus, some of which cause disease.

    "'This again,' said the Bacteriologist, slipping a glass slide under the microscope, 'is a preparation of the celebrated Bacillus of cholera - the cholera germ.'"

  2. 2
    aerobic rod-shaped spore-producing bacterium; often occurring in chainlike formations; found primarily in soil wordnet
  3. 3
    Any bacilliform (rod-shaped) bacterium.
  4. 4
    Something which spreads like bacterial infection. broadly, figuratively

    "The “bacillus of boom or depression,” he wrote, travels freely “from country to country.”"

Synonyms

All synonyms
adenovirusaerobeaerobic bacteriaamebicamoebaanaerobe

Example

More examples

"The bacillus Calmette-Guérin (BCG) vaccine for tuberculosis causes front-line immune cells to make long-lasting biological “marks” on their DNA, changing how they read genetic instructions for fighting off viruses, the researchers say."

Etymology

Learned borrowing from Latin bacillus (“little staff, wand”), diminutive of baculum (“stick, staff, walking stick”).

Related phrases

Döderlein's bacillusEberth's bacillusKlebs-Löffler bacillusKoch's bacilluscomma bacillus

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Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.