What does spirillum mean?
A spirillum is a microorganism with a long, spiral or corkscrew-shaped body. The term is used especially for bacteria whose rigid, twisting form distinguishes them from other spiral-shaped organisms such as flexible spirochetes. In modern biological writing, the lowercase word commonly refers to a body form rather than to a particular taxonomic group; the capitalized Spirillum may also appear in older names and classifications. The plural is spirilla, and the related adjective spirillar describes structures or organisms bearing spiral-shaped forms. Though encountered chiefly in microbiology and historical taxonomy, spirillum is useful for understanding a distinctive microbial shape that can be seen clearly under a microscope. Its unusual name effectively combines the scientific idea of a tiny spiral with the familiar visual image of a corkscrew.
nounA bacterium or other microorganism with a spiral or corkscrew-shaped body. The capitalized form Spirillum is also used as the name of a former bacterial genus.
- Any bacterium or other microorganism whose body is characteristically spiral-shaped.
- A member of the formerly recognized bacterial genus Spirillum.
"Under the microscope, the spirillum twisted gently as it moved through the water."
"Researchers identified a free-living spirillum in the sediment sample."
"The organism belongs to Spirillum, a group distinguished by its rigid spiral form."
The plural changes the ending to -a and is pronounced /spɪˈrɪlə/. In biological descriptions, it can refer to several spiral-shaped microorganisms collectively.
"Numerous spirilla were visible in the microscopic sample."
A spirillum puts the familiar corkscrew shape into the microscopic world.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does spirillum come from?
Spirillum comes through New Latin from Latin spirillum, a diminutive of spira, meaning “coil” or “spiral.” The same Latin root also underlies English words such as spiral and spire. In biological usage, the term developed as a name for spiral-shaped bacteria, later becoming associated with the bacterial genus Spirillum.
Related word forms
How spirillum is actually used
This is a specialized biological term and is uncommon outside microbiology. The lowercase spirillum is generally used for the spiral body form, while the capitalized Spirillum may refer to the historical genus.
Easily confused with spirillum
A spirillum is the singular noun, while spirilla is its plural form.