bacillus

noun

ba·​cil·​lus bə-ˈsi-ləs How to pronounce bacillus (audio)
plural bacilli bə-ˈsi-ˌlī How to pronounce bacillus (audio)
 also  -lē
1
: any of a genus (Bacillus) of rod-shaped gram-positive usually aerobic bacteria producing endospores and including many saprophytes and some parasites (such as B. anthracis of anthrax)
broadly : a straight rod-shaped bacterium
2
: bacterium
especially : a disease-producing bacterium

Examples of bacillus in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Another option that is also safe and environmentally friendly is a product containing BT, bacillus thuringiensis. Chris McKeown, The Enquirer, 10 Aug. 2024 Gut Guru Gummies contain up to 2 billion CFU of bacillus coagulans because good bacteria is key for a balanced gut. Amber Smith, Discover Magazine, 29 Oct. 2022 Key ingredients: Glyceryl glucoside, hydrolyzed yeast extract, bacillus ferment, polyglucuronic acid Size: 0.67 Fl. Iman Balagam, harpersbazaar.com, 6 May 2023 Recent analyses of global epidemiological data by several teams in the United States and in Israel found that in places with higher rates of bacillus Calmette-Guérin (BCG) tuberculosis vaccination, the spread of COVID-19 is slower and pandemic death rates are lower. Quanta Magazine, 14 Sep. 2020 See all Example Sentences for bacillus 

Word History

Etymology

New Latin, from Medieval Latin, small staff, rod, diminutive of Latin baculus staff, alteration of baculum

First Known Use

1868, in the meaning defined at sense 1

Time Traveler
The first known use of bacillus was in 1868

Dictionary Entries Near bacillus

Cite this Entry

“Bacillus.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/bacillus. Accessed 13 Dec. 2024.

Kids Definition

bacillus

noun
ba·​cil·​lus bə-ˈsil-əs How to pronounce bacillus (audio)
plural bacilli -ˈsil-ˌī How to pronounce bacillus (audio)
 also  -ˈsil-ē
: any of numerous straight rod-shaped bacteria that require oxygen for growth
also : a disease-producing bacterium

Medical Definition

bacillus

noun
ba·​cil·​lus bə-ˈsil-əs How to pronounce bacillus (audio)
plural bacilli
-ˌī also -ē
1
a
capitalized : a genus of rod-shaped gram-positive endospore-producing usually aerobic bacteria of the family Bacillaceae that include many saprophytes and some parasites (as B. anthracis of anthrax)
b
: any bacterium of the genus Bacillus
broadly : a straight rod-shaped bacterium
2
: bacterium
especially : a disease-producing bacterium

More from Merriam-Webster on bacillus

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!