cis

/sɪs/

//sɪs// adj

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

"cis" is a 3-letter English headword indexed on PlainSpell.

The verdict

“cis” sits in 20 confusable pairs (corpus #13,115) as an adjective. The look-alike neighbours are the real trap.

#13,115
frequency rank, English
5,599
“C” headwords
20
confusable pairs

According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - Having two mutations on two genes on the same chromosome of a homologous pair.

Corpus desk

Index EN-cis · cis · English

cis · rank #13,115 · 0 variants · 20 confusables

  • FREQ-MID #13,115
  • LEN-MID 3 letters
  • VOW-1 1 vowel
  • CONFUS-HIGH 20 pairs
  • VAR-0 0 variants
  • BOOK-DENSE 5,599
  • PHOTO-FINISH chamberlain

Nearest frequency peer: chamberlain (-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.

Frequency neighbours of confusable “cis”

Peers at similar corpus weight, separate from look-alike pairs below

corpus weight

What this shows Bars place “cis” against nearest ranked English headwords, not a reprint of the confusable-pair desk.

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).

cis vs co
33% similar
cis vs CM
0% similar
cis vs CT
0% similar

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

Key facts for cis
PropertyValue
Headwordcis
LanguageEnglish
Part of speechAdjective
IPA/sɪs/
Letters3
Frequency rank#13,115
Misspellings tracked0
Confusable pairs20
SourceWiktionary (kaikki.org)

Corpus rank beside confusables of “cis”

This scale runs from the tiny cluster of words that carry ordinary speech (left) to the long tail of words almost nobody reaches for (right).cislands here:

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

Ticks step logarithmically, so each one marks a roughly tenfold drop in how often the word turns up. Same rarity band neighbours include “chamberlain” (#13,114), “claw” (#13,116), “CDC” (#13,113). Among 5,599 “C” headwords, “cis” is #13,115. Source: FrequencyWords open word-frequency list.

Easy to mix with look-alikes

The spelling risk for cis is neighbouring look-alikes ("co", "CM", …), not just typos; it is anadjective pronounced /sɪs/. Frequency #13,115 among 5,599 “C” headwords. 4 recorded senses keep meaning in play.

cis has no tracked misspelling variants, since its letter sequence doesn't invite the usual edit-distance slips. It also participates in 20 confusable-pair relationships, "co", "CM", "CT", 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 cis (“on this side (of), on the near or same side”). Doublet of he, it, here, hither, and hence. The correct English form is cis, spelled C-I-S.

Definition

  1. 1
    Having two mutations on two genes on the same chromosome of a homologous pair.
  2. 2
    Of the side of the Golgi apparatus nearer to the endoplasmic reticulum.
  3. 3
    In (or constituting, forming, or describing) a double bond in which the greater radical on both ends is on the same side of the bond.
  4. 4
    In (or constituting, forming, or describing) a coordination compound in which the two instances of a particular ligand are adjacent to each other.

Recorded use

Wiktionary examples

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

  1. 9 is thought to survive longer when the CH = CH bond is cis and to favour the formation of another cis double bond in a propagation reaction involving its displacement by monomer. 10, on the other hand, is more likely to yield a trans double bond […]
  2. However, a cis double bond causes a kink in the chain. (A cis double bond introduces a bend of about 42 into the linear hydrocarbon chain.)

Etymology

From Latin cis (“on this side (of), on the near or same side”). Doublet of he, it, here, hither, and hence.

Antonyms

trans

This word in other languages

cis(Français)

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 "cis"?
"cis" is spelled C-I-S. The IPA pronunciation is /sɪs/.
What does "cis" mean?
As an adjective, "cis" means: Having two mutations on two genes on the same chromosome of a homologous pair.
What words are commonly confused with "cis"?
"cis" is commonly confused with "co", "CM", "CT". These words look or sound similar but have different meanings. PlainSpell provides detailed comparisons for each pair.
How do you pronounce "cis"?
The IPA (International Phonetic Alphabet) transcription for "cis" is /sɪs/. 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 "cis"?
From Latin cis (“on this side (of), on the near or same side”). Doublet of he, it, here, hither, and hence. 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 "cis", not the corpus desk frequency band.

Same letter count

Frequency-ranked English headwords with 3 letters (nearest by frequency rank).

CDC#13,113FLA#13,151Wes#13,079GTA#13,166

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

Source: FrequencyWords open word-frequency list