What does "cardio" mean?

Exercise with the goal of raising the heart rate.

Cardio

Common synonyms include: aerobic activity, aerobic exercise, aerobic workout, aerobics, cardiac, cardiology.

/ˈkɑɹ.di.oʊ/ adj, noun

adj, noun ·Uncommon ·Advanced level

Noun

1
Exercise with the goal of raising the heart rate. uncountable, usually
"I did some cardio today instead of lifting weights."

Adjective

1
Cardiovascular; pertaining to the health of the circulatory and respiratory systems. not-comparable

"If you're not sweating when you do cardio, then you're not doing it hard enough."

Clipping of cardiovascular.