serum

/ˈsɪəɹəm/

//ˈsɪəɹəm// noun

By · According to Wiktionary data (CC BY-SA) ·

"serum" is a 5-letter English headword indexed on PlainSpell.

The verdict

“serum” has 7 generated spelling variants in the English index at frequency #10,609. The variants make it a useful spelling check.

#10,609
frequency rank, English
6,566
“S” headwords
7
tracked misspellings
20
confusable pairs

According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - Ellipsis of blood serum.

Corpus desk

Index EN-serum · serum · English

serum · rank #10,609 · 7 variants · 20 confusables

  • FREQ-MID #10,609
  • LEN-MID 5 letters
  • VOW-2 2 vowels
  • CONFUS-HIGH 20 pairs
  • VAR-MID 7 variants
  • BOOK-DENSE 6,566
  • PHOTO-FINISH seizure

Nearest frequency peer: seizure (-1 rank slots)

Read with this headword: Spelling guide for this pattern

Desk codes from Wiktionary headword shape, FrequencyWords rank tier, confusable-pair count, generated misspelling depth, letter-cohort book size, and photo-finish peer. Not a difficulty grade.

Rank peers near misspelling magnet “serum”

Same rarity band: useful when a typo lands on a peer headword

corpus weight

What this shows “serum” sits among these FrequencyWords peers; misspelling depth is tracked separately in the edit-distance chart.

Source FrequencyWords open word-frequency list As of September 3, 2026

Visual similarity to commonly confused words

How many letter changes separate each confused pair (Levenshtein distance, normalized).

serum vs sum
60% similar
serum vs slum
60% similar
serum vs serve
60% similar

Source: PlainSpell confusable corpus (Wiktionary, CC BY-SA).

Key facts for serum
PropertyValue
Headwordserum
LanguageEnglish
Part of speechNoun
IPA/ˈsɪəɹəm/
Letters5
Frequency rank#10,609
Misspellings tracked7
Confusable pairs20
SourceWiktionary (kaikki.org)

Frequency seat of misspelling magnet “serum”

Every-word frequency runs from the handful of words we use constantly (left) to the long tail used once in a blue moon (right).serumlands here:

#1#100#1K#10K#100K
← used constantlyrarely used →

Scale is logarithmic (each tick is 10× rarer). Same rarity band neighbours include “seizure” (#10,608), “singular” (#10,610), “scrutiny” (#10,607). Among 6,566 “S” headwords, “serum” is #10,609. Source: FrequencyWords open word-frequency list.

A misspelling magnet

The generator records 7 spelling variants around serum (IPA /ˈsɪəɹəm/), anoun. Corpus frequency is #10,609 among 6,566 “S” headwords. Wiktionary lists 5 senses, so context still picks the gloss.

Our generated misspelling index lists 7 likely wrong-spelling variants for serum, with forms such as "esrum", "sermu", and "serrum". Each of these forms differs from the correct spelling by one small edit: a doubled letter, a dropped silent letter, or a substituted vowel. It also participates in 20 confusable-pair relationships, "sum", "slum", "serve", and more, since the words sound or look close enough that writers reach for the wrong one mid-sentence.

Etymologically, the entry records: From Latin serum (“whey”). Cognates include French sérum, Spanish suero, Italian siere, siero, Portuguese soro. Doublet of suero. The correct English form is serum, spelled S-E-R-U-M.

Definition

  1. 1
    Ellipsis of blood serum.
  2. 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).
  3. 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. 4
    The watery portion of certain other animal fluids, such as milk; whey.
  5. 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.

Recorded use

Wiktionary example

These source excerpts show how serum appears in context. They illustrate usage; the definition above remains the entry’s reference meaning.

  1. Near-synonym: antiserum

Etymology

From Latin serum (“whey”). Cognates include French sérum, Spanish suero, Italian siere, siero, Portuguese soro. Doublet of suero.

This word in other languages

suero(Español)sérum(Français)Serum(Deutsch)sérum(Português)

Common misspellings

Also misspelled as:

  • esrum
  • sermu
  • serrum
  • serumm
  • seurm
  • sreum
  • sserum

Misspelling Pattern Breakdown

How far each generated variant is from the correct spelling of serum - expressed in single-character edits (insert, delete, or swap one letter). Bigger bars stand out at a glance; a one-edit slip is the hardest to catch.

esrum2sermu2serrum1serumm1seurm2sreum2sserum1
Edit distance from "serum"

Definitions, pronunciation, and etymology for this entry are drawn from Wiktionary via the kaikki.org structured extract (CC BY-SA); frequency ordering uses the FrequencyWords open word-frequency list (2018 English corpus, MIT). See the methodology for how each field is sourced and updated.

Frequently Asked Questions

How do you spell "serum"?
"serum" is spelled S-E-R-U-M. The IPA pronunciation is /ˈsɪəɹəm/.
What does "serum" mean?
As a noun, "serum" means: Ellipsis of blood serum.
What words are commonly confused with "serum"?
"serum" is commonly confused with "sum", "slum", "serve". These words look or sound similar but have different meanings. PlainSpell provides detailed comparisons for each pair.
How do you pronounce "serum"?
The IPA (International Phonetic Alphabet) transcription for "serum" is /ˈsɪəɹəm/. Click the speaker icon on the pronunciation badge above to hear it spoken aloud where audio is available.
What is the origin of the word "serum"?
From Latin serum (“whey”). Cognates include French sérum, Spanish suero, Italian siere, siero, Portuguese soro. Doublet of suero. See the full etymology section above for more details.
Is PlainSpell free to use?
Yes, PlainSpell is a completely free word reference. You can look up definitions, pronunciations, confusable pairs, homophones, and spelling corrections across 5 languages without any sign-up or subscription.

Similar English words by spelling shape

Same letter count and similar misspelling depth for "serum", not the corpus desk frequency band.

Same letter count

Frequency-ranked English headwords with 5 letters (nearest by frequency rank).

skate#10,611Scots#10,606Sofia#10,612salty#10,605

Similar misspelling depth

Headwords with a similar count of attested misspellings (7 here; floor ≥5).

tempo7 variantsrainy7 variantsturbo7 variantsPayne7 variants

Source: Wiktionary (via kaikki.org) Structured Wiktionary extract

Source: FrequencyWords open word-frequency list