noun, plural bacilli [buh-sil-ahy] .
any rod-shaped or cylindrical bacterium of the genus Bacillus, comprising spore-producing bacteria. See diag. under bacteria.
(formerly) any bacterium.

1880–85; < Late Latin, variant of Latin bacillum (diminutive of baculum) staff, walking stick Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
Cite This Source Link To bacilli
World English Dictionary
bacillus (bəˈsɪləs)
n , pl -cilli
1.  coccus Compare spirillum any rod-shaped bacterium, such as a clostridium bacterium
2.  any of various rodlike spore-producing bacteria constituting the family Bacillaceae, esp of the genus Bacillus
[C19: from Latin: a small staff, from baculum walking stick]

Collins English Dictionary - Complete & Unabridged 10th Edition
2009 © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009
Cite This Source
Word Origin & History

1883, from Mod.L., "little rod," from L.L. bacillus "wand," lit. "little staff," dim. of baculum "a stick," from PIE base *bak- "staff," also source of Gk. bakterion (see bacteria). Introduced as a term in bacteriology 1853 by Ger. botanist Ferdinand Cohn (1828-1898).

pl. of bacillus (q.v.).
Online Etymology Dictionary, © 2010 Douglas Harper
Cite This Source
American Heritage
Medical Dictionary

bacillus ba·cil·lus (bə-sĭl'əs)
n. pl. ba·cil·li (-sĭl'ī')

  1. Any of various rod-shaped, usually gram-positive aerobic bacteria of the genus Bacillus that often occur in chains and include Bacillus anthracis, the causative agent of anthrax.

  2. Any of various bacteria, especially a rod-shaped bacterium.

Bacillus (bə-sĭl'əs)
A genus of rod-shaped gram-positive bacteria capable of producing endospores.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
Cite This Source
American Heritage
Science Dictionary
bacillus   (bə-sĭl'əs)  Pronunciation Key 
Plural bacilli (bə-sĭl'ī')
Any of various pathogenic bacteria, especially one that is rod-shaped.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
Cite This Source
American Heritage
Cultural Dictionary
bacilli [(buh-sil-eye)]

sing. bacillus

One of three forms of bacteria, usually rod-shaped.

The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
Cite This Source
Example sentences
Bacteria which have flagella are either rod or spiral-shaped and are known as bacilli and spirochetes, respectively.
Copyright © 2014, LLC. All rights reserved.
  • Please Login or Sign Up to use the Recent Searches feature