noun · 2 senses · updated from the 2026-07-25 local source snapshot
Definitions and examples are grouped by meaning. Pronunciation, history, word forms, translations, descendants, synonyms, antonyms, derived terms, and related words appear whenever the source provides them.
Sound
Pronunciation
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Received-Pronunciation:/ˌdʌɪ.fɛnˈhʌɪ.dɹəm.iːn/
General-American:/ˌdaɪˌfɛnˈhaɪ.dɹəˌmiːn/
General-American:Recorded audio is listed in the source snapshot.
1
noun
Meaning 1
An antihistamine and anticholinergic drug that blocks the effect of histamine at H1 receptor sites, relieving allergy symptoms. It also reduces smooth muscle contraction, increases heart rate, and sedates the user by blocking muscarinic acetylcholine receptors (mAChRs).
Definition source: English Wiktionary via Wiktextract
Usage: countable, uncountable
Topics: medicine, pharmacology, sciences
Examples
Diphenhydramine is a convenient and cheap antihistamine for use, but there are other drugs that do not make the user tired.
Meaning relationships
Synonyms: ZzzQuil, Benadryl
Antonyms: none provided
2
noun
Meaning 2
antihistamine (trade name Benadryl) used to treat allergic reactions involving the nasal passages (hay fever) and also to treat motion sickness
Definition source: Princeton WordNet 3.0
No example sentence was provided for this meaning.
Meaning relationships
Synonyms: Benadryl
Antonyms: none provided
Broader terms: antihistamine
History
Etymology
Etymology tree Proto-Indo-European *dwóh1 Proto-Indo-European *dwi- Proto-Hellenic *dwi- Ancient Greek δῐ- (dĭ-)bor. Latin di-bor. English di- Proto-Indo-European *bheh2-der. Proto-Hellenic *pháňňō Ancient Greek φαίνω (phaínō)der. French phéno- Proto-Indo-European *swel-der.? Ancient Greek ῡ̔́λη (hū́lē)der. French -yle French phénylebor. English phenyl English diphen(yl) English (benz)hydr(yl) Egyptian jmnbor. Ancient Greek Ᾰ̓́μμων (Ắmmōn)bor. Latin Ammōn Latin ammoniacusder. English ammonia Proto-Indo-European *-nós Proto-Indo-European *-iHnos Proto-Italic *-īnos Latin -īnusder. Old French -inbor. Middle English -in English -ine English amine English -amine English diphenhydramine From diphen(yl) + (benz)hydr(yl) + -amine.
Across languages
Translations
2 source translations are retained for this English entry.
Chinese Mandarin:
苯海拉明
(běnhǎilāmíng)
— antihistamine and sedative drug
Czech:
difenhydramin
— antihistamine and sedative drug
