Respiratory

Etymology

From Latin “respirare” (to breathe again or repeatedly), from “re-” (again) and “spirare” (to breathe). The “spirare” root is quietly everywhere — in “inspire,” “expire,” “conspire,” and “spirit,” which was once literally breath. Respiration is the breath taken again and again, life’s most relentless rhythm.

adjective · /RES-pur-uh-tor-ee/
Relating to breathing and the organs that carry it out — the nose, throat, airways, and lungs.
What it names
The whole apparatus of breathing as one system, which is why a “respiratory infection” can mean anything from a head cold to pneumonia, all along the same connected passage.
Example
During flu season the ward filled with patients suffering respiratory illnesses, from mild coughs to serious pneumonia.
Related idea
The respiratory system handles breathing; the cardiovascular system handles circulation. They work in tandem — the lungs oxygenate the blood the heart then pumps — so a failure in one quickly stresses the other.