Epinephrine

Etymology

From Greek "epi-" (upon) and "nephros" (kidney), because the adrenal glands that make it sit atop the kidneys. Its everyday twin "adrenaline" says the same thing in Latin ("ad-" toward, "ren" kidney); "epinephrine" prevailed in American medicine partly because "Adrenalin" was once a trademark.

noun · /ep-ih-NEF-rin/
The hormone released in stress that speeds the heart, opens the airways, and readies the body for action.
What it names
The body's emergency chemical — the driver of the fight-or-flight surge — under its clinical name.
Example
The nurse jabbed the epinephrine into his thigh and his collapsing airway began to reopen within seconds.
Related idea
Epinephrine and adrenaline are two names for the identical molecule — the first Greek, the second Latin — a rare case where a single substance carries two full names for reasons of geography and trademark rather than chemistry.