complex

/ˈkɒmplɛks/

//ˈkɒmplɛks// adj

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

"complex" is a 7-letter English headword indexed on PlainSpell.

The verdict

“complex” is a regularly-used English word, ranked #1,449 in English word frequency and used as an adjective.

#1,449
frequency rank, English
7
letters
11
tracked misspellings
12
confusable pairs

According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - Made up of multiple parts; composite; not simple.

Visual similarity to commonly confused words

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

complex vs couple
71% similar
complex vs comply
71% similar
complex vs Copley
57% similar

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

Key facts for complex
PropertyValue
Headwordcomplex
LanguageEnglish
Part of speechAdjective
IPA/ˈkɒmplɛks/
Letters7
Frequency rank#1,449
Misspellings tracked11
Confusable pairs12
SourceWiktionary (kaikki.org)

Where “complex” sits in English frequency

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

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

Scale is logarithmic (each tick is 10× rarer). Source: FrequencyWords open word-frequency list.

Spelling & Dictionary Insight

The English entry for complex is 7 letters long, classified as an adjective, and transcribed in the International Phonetic Alphabet as /ˈkɒmplɛks/. Corpus data places it at rank #1,449 in overall English word frequency, indicating it appears regularly in written and spoken text. Wiktionary records 6 distinct senses for this headword, so context determines which meaning a reader should apply.

Our generated misspelling index lists 11 likely wrong-spelling variants for complex, with forms such as "ccomplex", "cmoplex", and "comlpex". 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 12 confusable-pair relationships, "couple", "comply", "Copley", and more, where similar look or sound leads writers to substitute one word for another in context.

Etymologically, the entry records: From French complexe, from Latin complexus, past participle of complector (“to entwine, encircle, compass, infold”), from com- (“together”) and plectō (“to weave, braid”). May be analyzed as com- + -plex. See complect. Doublet of complexus. The correct English form is complex, spelled C-O-M-P-L-E-X.

Definition

  1. 1
    Made up of multiple parts; composite; not simple.
  2. 2
    Not simple, easy, or straightforward; complicated.
  3. 3
    Having the form a + bi, where a and b are real numbers and i is (by definition) the imaginary square root of −1.
  4. 4
    Whose range is a subset of the complex numbers.
  5. 5
    Whose coefficients are complex numbers; defined over the field of complex numbers.
  6. 6
    A curve, polygon or other figure that crosses or intersects itself.

Etymology

From French complexe, from Latin complexus, past participle of complector (“to entwine, encircle, compass, infold”), from com- (“together”) and plectō (“to weave, braid”). May be analyzed as com- + -plex. See complect. Doublet of complexus.

Synonyms

complexcomplexedcomplicatecomplicatedconvolutedGordianinvoluteintricateinvolutionalinvolvedknottylabyrinthallabyrinthinemanifold

Antonyms

incomplexnoncomplexnoncomplicatedsimplesimplexstraightforwarduncomplexuncomplexeduncomplicatedunconvoluted

This word in other languages

complicado(Español)complexe(Français)kompliziert(Deutsch)complexo(Português)

Common misspellings

Also misspelled as: ccomplex,cmoplex,comlpex,commplex,compelx,complexx,compllex,complxe,compplex,copmlex,ocmplex

Misspelling Pattern Breakdown

How far each generated variant is from the correct spelling of complex - counted as single-character edits (an insertion, a deletion, or a substituted letter). The larger the bar, the easier the typo is to spot; one-edit slips are the ones that sneak past readers.

ccomplex1cmoplex2comlpex2commplex1compelx2complexx1compllex1complxe2
Edit distance from "complex"

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 "complex"?
"complex" is spelled C-O-M-P-L-E-X. The IPA pronunciation is /ˈkɒmplɛks/.
What does "complex" mean?
As an adjective, "complex" means: Made up of multiple parts; composite; not simple.
What words are commonly confused with "complex"?
"complex" is commonly confused with "couple", "comply", "Copley". These words look or sound similar but have different meanings. PlainSpell provides detailed comparisons for each pair.
How do you pronounce "complex"?
The IPA (International Phonetic Alphabet) transcription for "complex" is /ˈkɒmplɛks/. 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 "complex"?
From French complexe, from Latin complexus, past participle of complector (“to entwine, encircle, compass, infold”), from com- (“together”) and plectō (“to weave, braid”). May be analyzed as com- + -plex. See complect. Doublet of complexus. 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.

Using “complex”

The practical upshot for anyone who landed here from a spell-check.

  • The one correct English spelling is C-O-M-P-L-E-X - every other letter order is a misspelling in standard orthography.
  • Say it as /ˈkɒmplɛks/ (IPA); tap the speaker on the pronunciation badge to hear it where audio exists.
  • Don't mix it up with “couple” - see the side-by-side comparison. complex vs couple
  • Browse more English words and confusable pairs in the same reference. English words
Data Source

Wiktionary (via kaikki.org), licensed under CC BY-SA & GFDL. Word ordering uses an open word-frequency list; misspelling variants are generated by edit-distance from the correct headword.

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

Source: FrequencyWords open word-frequency list FrequencyWords open word-frequency list