cardio

¹ American  

[kahr-dee-oh] / ˈkɑr di oʊ /

noun

Informal.

1. aerobic exercise that stimulates and strengthens the heart and lungs.

   I mostly use weights, but I always add a little cardio into my routine.

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adjective

Informal.

1. of or relating to aerobic exercise.

   The class begins with a slow and steady warmup, and then it switches to a cardio workout.

2. of or relating to the heart; cardiovascular.

   He's a hugely successful cardio surgeon.

cardio- ² American  

1. a combining form meaning “heart,” used in the formation of compound words.

   cardiogram.

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cardio- British  

combining form

1. heart

   cardiogram

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Usage

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.

Etymology

Origin of cardio¹

First recorded in 1960–65

Origin of cardio-²

< Greek kardio-, combining form of kardía

Example Sentences

This Shakespearean traveling show, now at the Montalbán Theatre in Hollywood through Saturday, is a daredevil feat of memory, theatrical bravado and cardio fitness.

From Los Angeles Times • Jan. 25, 2026

I’m very much a morning exercise person, so after I wash my face and brush my teeth, my first priority is my cardio or my strength training.

From The Wall Street Journal • Jan. 5, 2026

Strength training, cardio and yoga are part of our fitness activities every week.

From MarketWatch • Jan. 2, 2026

Benn failed to use his speed and cardio to overwhelm Eubank and will be eager to rectify that.

From BBC • Nov. 10, 2025

He slows quickly, though, as if it’s been millennia since he’s done any cardio.

From "Kwame Crashes the Underworld" by Craig Kofi Farmer