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a combining form meaning “vessel,” used in the formation of compound words: vasoconstrictor.
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Also especially before a vowel, vas-.

Origin of vaso-

<Latin vās vessel + -o-
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2022


What does vaso- mean?

Vaso- is a combining form used like a prefix meaning “vessel,” typically referring to blood vessels, such as veins and arteries. It is often used in medical terms, especially in anatomy.

In some instances, such as vasotomy, vaso- specifically refers to the vas deferens, the duct that carries sperm to the penis.

Vaso- comes from the Latin vās, meaning “vessel.” The Latin vās is also the source of the word vase, which is, after all, a type of vessel—often for flowers! And the diminutive form of vās is vāsculum, literally “little vessel”; it’s the source of the word vascular, commonly encountered in cardiovascular.

Learn more about cardio- at our Words That Use cardio- and Words That Use cardi- articles.

What are variants of vaso-?

When combined with words or word elements that begin with a vowel, vaso- becomes vas-, as in vasectomy.

Examples of vaso-

One medical term that features vaso- is vasoconstriction, which is the constriction (“drawing or pressing in”) of the blood vessels (vaso-). When vasoconstriction happens, blood pressure increases.

The opposite of vasoconstriction is vasodilation, the dilation (“widening or expanding”) of blood vessels, which is often done with drugs to help manage blood pressure.

Knowing a little etymology can indeed help make hard words like vasoconstriction and vasodilation more manageable.

What are some words that use the combining form vaso-?

Break it down!

Given that vaso- means “(blood) vessel,” what does the procedure of a vasopuncture involve?

How to use vaso- in a sentence

British Dictionary definitions for vaso-


before a vowel vas-

combining form
indicating a blood vesselvasodilator
indicating the vas deferensvasectomy

Word Origin for vaso-

from Latin vās vessel
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medical definitions for vaso-


Blood vessel:vasoconstriction.
Vas deferens:vasectomy.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.