complex (English)

Where does "complex" come from?

The English adjective 'complex' entered the language as a borrowing from French 'complexe'[1][3], which is a learned borrowing from Latin 'complexus'[3]. The Latin term 'complexus' is the past participle of 'completor'[1], meaning 'I entwine, encircle, compass, infold'[1][2], and is formed from 'com-' meaning 'together'[1][2] and 'plectere' meaning 'to weave, braid'[1] or 'plecto'[2]. Ultimately, these Latin and Romance forms trace back to the Proto-Indo-European root '*pleḱ-' meaning 'to fold, weave'[4][6], which itself extends from '*pel-' meaning 'to wrap'[4][6].

Open questions

The Proto-Indo-European root '*pleḱ-' is reconstructed as an extension of another root '*pel-'. [4] [6]

Full etymology tree

complex (English), 'Made up of multiple parts; composite; not simple.'
- borrowed complexe (French), 'complex, not simple'
  - learned borrowing complexus (Latin), 'embraced'
    - derived complector (Latin), 'to embrace or hug'
      - prefix com- (Latin), 'allomorph of con-'
      - affix plecto (Latin), 'to plait, weave, braid'
        derived *plektō (Proto-Italic)
        derived *pleḱ- (Proto-Indo-European), 'to fold, plait, weave'
        derived *pel- (Proto-Indo-European), 'to cover, to wrap'

Ancestors

*pleḱ- (Proto-Indo-European)
complexe (French)
complexus (Latin)
com- (English)
-plex (English)

Cognates and doublets

complexus (English)

Descendants and derived words

bicomplex (English)
complex analysis (English)
complex compound (English)
complex conjugate (English)
complex conjugate root theorem (English)
complex conjugation (English)
complex-differentiable (English)
complex fraction (English)
complex function (English)
complex geometry (English)
complexification (English)
complexified (English)

Related words

Sources

Updated October 2026

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Etymology data from Wiktionary, CC BY-SA 4.0 · About Miraris