What does the prefix quad- mean?
Quad- (or quadr-) comes from the Latin quattuor, which means "four". It shows that something has four parts, sides or units.
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Prefix · quantity · four
quad-/quadr-
Means "four": quadrant, quadruple, quadrilateral, quadruped, quadruplets, quadriceps.
Basic
Written by Bryan López, English teacher · Updated
Quad- or tetra-: two ways to say four
Quad- is the Latin version of "four", and tetra- is the Greek version: both mean the same. They are used in different words, and in general quad- appears in geometry, biology and the anatomy of the body, while tetra- is more frequent in chemistry. Before a vowel, quad- is spelled quadr-.
How it is used
Attaches to nouns to indicate "four" or "fourfold":
- quad- + rootrant → quadrantruple → quadrupleruped → quadrupedriceps → quadriceps
- quadr- + vowelilateral → quadrilateralangle → quadrangleennial → quadrennial
Pronunciation: /kwɒd/. The variant "quadr-" appears before vowels: quadrilateral, quadrangle. Latin equivalent of Greek tetra-.
How it is pronounced
quad-/quadr-/kwɒd/
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Examples
Root word
With quad-/quadr-
In a phrase
- rantquadrantThe city is divided into four quadrants by the main roads.
- ruplequadrupleSales quadrupled in the first year after the product launch.
- rilateralquadrilateralA square is a quadrilateral with four equal sides and angles.
- rupedquadrupedA horse is a quadruped — it walks on four legs.
- rupletsquadrupletsShe gave birth to quadruplets, which surprised even her doctors.
- ricepsquadricepsHis quadriceps were sore after the long uphill run yesterday.
- ranglequadrangleStudents ate lunch in the quadrangle between the college buildings.
Common mistakes
quad- and tetra- are interchangeable
quad-/quadr- is Latin (quadrant, quadruple, quadruped); tetra- is Greek (tetrahedron, tetrachloride, tetrapod) — not interchangeable
Both mean "four" but come from different languages. Words of Latin origin take quad-; words of Greek origin take tetra-. "Quadrahedron" and "tetrangle" are not words. The number prefix pattern in English follows the root language: Latin words use uni-(1), bi-(2), tri-(3), quad-(4); Greek words use mono-(1), di-(2), tri-(3), tetra-(4).
A trick to remember it
Picture a four-sided shape: quad- = four. quadrilateral, quadruple.
Practise what you learned
Exercise 1 · Form the word
Exercise 2 · Pick the right one
What is the difference between "quad-" and "tetra-"?
Frequently asked questions
What does the prefix quad-/quadr- mean in English?
The prefix quad-/quadr- means "four": quadrant, quadruple, quadrilateral, quadruped, quadruplets, quadriceps.
How do you pronounce quad-/quadr-?
The prefix quad-/quadr- is pronounced /kwɒd/. For example, "quadrant".
Can you give an example of a word with quad-/quadr-?
"rant" becomes "quadrant". It is a typical example of the quad-/quadr- prefix.
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