From French complexe, from Latin complexus, past participle of complector, from com- ("together") and plectere ("to weave, braid").

Adjective

• (British) IPA: /ˈkɒm.plɛks/, /kəmˈplɛks/
• (US) enPR: kəmplĕks, kŏm'plĕks; IPA: /kɑmˈplɛks/, /kəmˈplɛks/, /ˈkɑmplɛks/

Noun

• (British) IPA: /ˈkɒm.plɛks/
• (America) enPR: kŏm'plĕks, IPA: /ˈkɑmplɛks/

complex (comparative complexer, superlative complexest)

1. Made up of multiple parts; composite; not simple.

   a complex being; a complex idea

   • 1689 (indicated as 1690), [John Locke], chapter 2, in An Essay Concerning Humane Understanding. […], London: […] Eliz[abeth] Holt, for Thomas Basset, […], →OCLC ↗, book I, page 12 ↗:

     Ideas thus made up of several simple ones put together, I call complex; such as beauty, gratitude, a man, an army, the universe.

2. Not simple, easy, or straightforward; complicated.
   • 1837, William Whewell, “Inductive Epoch of Hipparchus”, in History of the Inductive Sciences, from the Earliest to the Present Times. […], volume I, London: John W[illiam] Parker, […]; Cambridge, Cambridgeshire: J. and J. J. Deighton, →OCLC ↗, book III (History of Greek Astronomy), section 2 (Estimate of the Value of the Theory of Eccentrics and Epicycles), page 183 ↗:

     If, when the actual motions of the heavens are calculated in the best possible way, the process is complex and difficult, and if we are discontented at this, nature, and not the astronomer, must be the object of our displeasure.

3. (mathematics, of a number) Having the form a + bi, where a and b are real numbers and i is (by definition) the imaginary square root of −1.

   complex number

   function of a complex variable

4. (mathematics, analysis, of a function) Whose range is a subset of the complex numbers.

   complex function

5. (mathematics, algebra) Whose coefficients are complex numbers; defined over the field of complex numbers.

   complex polynomial

   complex algebraic variety

6. (geometry) A curve, polygon or other figure that crosses or intersects itself.

• (not simple) complicated, detailed, difficult, hard, intricate, involved, tough

• (antonym(s) of “not simple”): basic, easy, simple, simplex, straightforward

• complexion
• (mathematics) symplectic

• French: complexe
• German: kompliziert
• Italian: complesso
• Portuguese: complexo
• Russian: сло́жный
• Spanish: complicado, complejo

• French: complexe
• German: kompliziert
• Italian: complicato
• Portuguese: complexo, complicado
• Russian: сло́жный
• Spanish: complicado

• French: complexe
• Italian: complesso
• Portuguese: complexo
• Russian: ко́мплексный
• Spanish: complexo

complex (plural complexes)

1. A problem. (clarification of this definition is needed)
2. A network of interconnected systems.

   military-industrial complex

3. A collection of buildings with a common purpose, such as a university or military base.
4. An assemblage of related things; a collection.
   • 1692–1717, Robert South, Twelve Sermons Preached upon Several Occasions, volume (please specify |volume=I to VI), London:

     This parable of the wedding supper comprehends in it the whole complex of all the blessings and privileges exhibited by the gospel.

   1. An organized cluster of thunderstorms.
   2. A cluster of wildfires burning in the same vicinity.

      The fire complex began as two separate fires.

   3. (taxonomy) A group of closely related species, often distinguished only with difficulty by traditional morphological methods.
5. (psychoanalysis) A collection of ideas caused by repressed emotions that leads to an abnormal mental condition

   Synonyms: constellation

6. (informal, by extension) A vehement, often excessive psychological dislike or fear of a particular thing.

   Jim has a real complex about working for a woman boss.

7. (chemistry) A structure consisting of a central atom or molecule weakly connected to surrounding atoms or molecules, as for example coordination compound#Noun in inorganic chemistry and protein complexes in biochemistry.
8. (math) A complex number.
9. (linguistics) A multimorphemic word, one with several parts, one with affixes.

• French: complexe
• French: complexe
• German: Komplex
• Italian: complesso
• Portuguese: complexo
• Russian: ко́мплекс
• Spanish: complejo

• French: complexe
• German: Komplex
• Italian: complesso
• Portuguese: complexo
• Russian: ко́мплекс
• Spanish: complejo

• French: complexe
• Italian: complesso
• Portuguese: composto, complexo
• Russian: ко́мплекс
• Spanish: complejo

complex (complexes, present participle complexing; simple past and past participle complexed)

1. (chemistry, intransitive) To form a complex with another substance
2. (transitive) To complicate.

• Italian: complessare