Hormone
Etymology
Coined in 1905 by physiologist Ernest Starling from Greek "hormon," the present participle of "horman" (to set in motion, urge on), from "horme" (impulse). The name captures the idea of a substance that spurs a far-off organ into action.
noun · /HOR-mohn/
A chemical messenger released into the blood by one part of the body to change how a distant part behaves.
What it names
Use it for the body’s slow, bloodstream-carried signaling — coordination across organs that nerves alone can’t reach.
Example
The hormone insulin, made in the pancreas, tells cells across the body to take in sugar.
Related idea
A hormone travels through blood and acts slowly on distant targets, whereas a neurotransmitter fires across a tiny gap between nerve cells almost instantly. Some molecules, like adrenaline, do both jobs depending on where they’re released.