quadr-

Quadr- is a combining form used like a prefix meaning “four.” It is used in a great variety of technical and scientific terms.

Quadr- comes from the Latin quattuor, meaning “four.” The Greek equivalent is tetra-, which also appears as tetr-, as in tetrahedron. Want to know more? Check out our Words That Use entries for tetr- and tetra-.

What are variants of quadr-?

Quadr- is a variant of quadri-, which loses its –i– when combined with words or word elements beginning with vowels.

In other instances, quadr- becomes quadra-, as in quadraphony.

Before some labial consonants (such as –p– or –f-), quadr- becomes quadru-, as in quadruplex, which uses the Latin equivalent of the form.

Want to learn more? Check out our Words That Use entries for quadra-, quadri-, and quadru-.

An example of a word that features quadr- is quadrangle, “a plane figure having four angles and four sides, as a square.” The word comes from the Latin quadrangulus, which uses the equivalent of the form quadr-.

As we have seen, the quadr- portion of the word means “four,” and -angle means “the space within two lines diverging from a common point.” Quadrangle literally translates to “four angles.”

What are some words that use the combining form quadr- or its equivalent in Latin?

• quadrant
• quadratic
• quadrel
• quadrella
• quadrennial 
• quadrominium

What are some other forms that quadr- may be commonly confused with?

• quasi-
• quinque-

The Latin combining form -ennial means “year.” With this in mind, how often does a quadrennial event take place?