Plural of Torus
For the mathematical and other dictionary senses covered here, “torus” forms the plural “tori.” The ending changes rather than simply adding -s, so write one torus and several tori.
The plural of “torus” is “tori” in the reviewed current dictionary treatment.
Key details
Choose the right form
| Meaning / situation | Form / construction | Decision |
|---|---|---|
| one object/form | torus | Use the singular. |
| two or more | tori | Use the recorded plural. |
| general -us rule | not reliable | Check each noun separately. |
Quick tests
Plural-choice test
Do you mean more than one torus?
If yes: Use “tori.”
If no: Use singular “torus.”
Caveat: The -us → -i pattern is not a universal English rule.
Examples
The model contains two tori.
“Tori” is the plural of “torus.”
A torus has a central hole.
One takes singular “torus.”
Several tori were rendered on screen.
The plural form is “tori.”
Further guidance
Core difference
Use “torus” for one and “tori” for more than one.
Fast Test
If the sentence refers to multiple torus-shaped objects or mathematical tori, use “tori.”
Usage Boundary
Do not assume every English noun ending in -us follows this pattern; this rule is lexical to “torus.”
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- TORUS | English meaning - Cambridge Dictionary (opens in a new tab)Cambridge University Press · Cambridge gives tori as the plural of torus.
- TORUS definition and meaning | Collins English Dictionary (opens in a new tab)HarperCollins Publishers · Collins likewise gives tori across the mathematical, architectural, botanical, anatomical and astronomical noun senses.