Antihistamine

Etymology

Built from “anti-” (against) and histamine, itself coined around 1910 from Greek “histos” (tissue, literally a web or loom) plus “amine,” because the compound was found throughout the body’s tissues. So an antihistamine is, transparently, an “against-tissue-amine” agent. The name records the discovery that allergy is a chemical overreaction, not a mysterious sensitivity.

noun · /an-tee-HIS-tuh-meen/
A drug that blocks histamine, the chemical the body releases during allergic reactions, easing sneezing, itching, and swelling.
What it names
The everyday allergy pill named for the exact thing it does — intercepting one specific signaling chemical — which is why the same drug helps hay fever, hives, and, as a side effect, sleep.
Example
One antihistamine cleared up the rash within an hour, though it left him too drowsy to drive.
Related idea
An antihistamine treats the reaction; it does not cure the underlying allergy, which is the immune system’s standing misjudgment about a harmless substance. Blocking histamine calms the symptoms without changing the sensitivity itself.