serum
/ˈsɪɹəm/noun
serum is spelled S-E-R-U-M: 5 letters and 2 syllables. It appears 5.5 times per million words in written English, the 10,519th most frequent word form (wordfreq, 2021 data). As a noun, serum means “Ellipsis of blood serum” (English Wiktionary, September 2026). The plural of serum is serums or sera.
How many letters and syllables are in serum?
| Letters | 5: S-E-R-U-M |
|---|---|
| Syllables | 2 (from its American pronunciation) |
| In writing | 5.5 times per million words; the 10,519th most frequent word form |
| Wrong spellings searched | none measured in search |
| Same letters |
Sources: letters and syllables from the English Wiktionary's hyphenation or pronunciation and the CMU Pronouncing Dictionary; written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media); rhymes and same-letter words are computed by PlainSpell from its own word list.
How common is serum?
Serum appears 5.5 times per million words in written English, the 10,519th most frequent word form in the list.
Source: written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media).
How do you pronounce serum?
- UK /ˈsɪəɹəm/
- UK /ˈsiːɹəm/
- US /ˈsɪɹəm/
Serum has 2 syllables (counted from its American pronunciation in the CMU Pronouncing Dictionary).
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Recordings: LL-Q1860_(eng)-Vealhurl-serum.wav, Wikimedia Commons (author and licence on each file's page).
What rhymes with serum?
No other word on PlainSpell ends in the same sounds as serum (/ɪɹəm/).
Spelled with the same letters in another order: muser, murse, merus, resum.
Computed by PlainSpell from the pronunciations in the English Wiktionary (dump of September 2, 2026): a rhyme shares every sound from the last stressed vowel to the end; ordered by written frequency (wordfreq 3.1).
Forms of serum
- serums plural
- sera plural
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).
What does serum mean?
The meanings the English Wiktionary records, quoted as written there (source below).
noun
- 1
Ellipsis of blood serum.
- 2
Blood serum used as a blood product, in the practice of medicine: blood serum from the tissues of immunized animals (human or nonhuman), containing antibodies and used to transfer immunity to another individual (human or nonhuman).
Near-synonym: antiserum
- 3
A watery liquid from animal tissue, especially one that moistens the surface of serous membranes or that is exuded by such membranes when they become inflamed, such as in edema or a blister.
- 4
The watery portion of certain other animal fluids, such as milk; whey.
- 5
A skincare product of varying consistencies with a high concentration of one or more active ingredients, for a targeted purpose, such as preventing acne, repairing sun damage, or moisturizing.
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).
Serum in Spanish, French, German and Portuguese
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Translations are Wiktionary's, by sense; a linked word has its own PlainSpell page.
Where does serum come from?
From Latin serum (“whey”). Cognates include French sérum, Spanish suero, Italian siere, siero, Portuguese soro. Doublet of suero.
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).