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.
"Cardiovascular fitness is the best indicator of current and future health. Good cardio fitness reduces the risk of over 30 lifestyle diseases as well as premature death by 40 to 50 percent," explained Wisløff.
From Science Daily • May 16, 2026
Noelle also implies — falsely — that cardio exercise can “throw your hormones off” and should be minimized, or even avoided.
From Salon • May 8, 2026
You might be forgiven for mistaking this as a nightclub but the 50 people - mostly women - are here for an hour of cardio and strengthening.
From BBC • Mar. 21, 2026
Peloton’s latest cardio machines have new Peloton IQ movement-tracking cameras in their screens.
From The Wall Street Journal • Jan. 4, 2026
They renovated it three years ago and practically quadrupled its size, putting in basketball courts, a saltwater pool, shiny new cardio equipment, and rows and rows of free weights.
From "Five Feet Apart" by Rachael Lippincott
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.
