of or relating to aerobic exercise.
The class begins with a slow and steady warmup, and then it switches to a cardio workout.
of or relating to the heart; cardiovascular.
He's a hugely successful cardio surgeon.
What does cardio- mean? Cardio- is a combining form used like a prefix meaning “heart.” It is used in many medical and scientific terms. Cardio- comes from the Greek kardía, meaning “heart.” In fact, the English word heart and the Greek kardía are related. Learn more at our entry for heart. What are variants of cardio-?When combined with words or word elements that begin with a vowel, cardio- becomes cardi-, as in cardiectomy.
First recorded in 1960–65
< Greek kardio-, combining form of kardía
Cardio is exercise that increases your heart rate: It gets your blood pumping. A little cardio, such as jogging or even dancing, can do a lot to keep your heart healthy as you age. Cardio means "heart," but it's used as shorthand for any exercise that works out your cardiovascular system, which includes the heart and blood vessels. Aerobic exercise, which increases how fast you breathe due to your body's need for more oxygen, is cardio, because when you breathe more, your heart pumps more. Aerobics and cardio are often used interchangeably. The term cardio is also an adjective that refers to anything related to the heart or to exercise that gives the heart a workout.
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Cardio activities such as running, swimming, and dancing appear to be especially effective at easing symptoms of depression and anxiety.
From Science Daily • Feb. 16, 2026
Cardio is not just good for my heart, but is a great emotional release and gets my endorphins going.
From The Wall Street Journal • Jan. 5, 2026
Cardio is important—but resistance training is where it’s at.
From Slate • Jan. 1, 2025
Cardio and weightlifting have become a part of my routine once the writers’ strike began.
From Los Angeles Times • Oct. 29, 2023
They gave guests a book of poems they had written, called “The Cardio Tesseract,” which they describe as “an ongoing collision” between their hearts and minds.
From Seattle Times • Oct. 22, 2021
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
