Definition of complex in English:

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Pronunciation: /ˈkɒmplɛks/


1Consisting of many different and connected parts: a complex network of water channels
More example sentences
  • The plant's shoots receive nourishment from a complex network of connections to the roots.
  • The hips, on the other hand, are a very large and complex joint with many different muscles and attachments.
  • As the vocal folds consist of a complex web of different muscle fibres, the tension and density of vocal folds can vary considerably.
1.1Not easy to analyse or understand; complicated or intricate: a complex personality the situation is more complex than it appears
More example sentences
  • Miller's writing is excellent, and he makes some rather complex biochemistry easy to understand.
  • In other words, the problems are much more complex than Mr. Baker understands or cares to discuss.
  • However, the whole matter of indirect tax liability is devilishly complex and difficult to understand.
2 Mathematics Denoting or involving numbers or quantities containing both a real and an imaginary part.
Example sentences
  • He also classified real and complex numbers into classes which are algebraically independent.
  • Bombelli was the first person to write down the rules for addition, subtraction and multiplication of complex numbers.
  • In addition to his work on geometry, Bolyai developed a rigorous geometric concept of complex numbers as ordered pairs of real numbers.
3 Chemistry Denoting an ion or molecule in which one or more groups are linked to a metal atom by coordinate bonds: in naming complex ions, the names of the ligands are cited first
More example sentences
  • Often the atoms comprising a complex molecule can be arranged in several ways and still satisfy the octet rule for each atom.
  • Carbohydrates can form more complex molecules when linked with other molecules.
  • This process occurs when oxygen atoms bond to an iron atom at the center of a complex protein molecule known as oxyhemoglobin.


1A group or system of different things that are linked in a close or complicated way; a network: a complex of mountain roads
More example sentences
  • ‘Network’ includes a complex of interconnected computer or communication systems of any type.
  • The complex of field systems and large stone walls extend from the north western slopes of Mount Brandon to within the boundaries of Dingle.
  • The wheel itself was split into many different complexes.
network, system, interconnected system/structure/scheme, nexus, web, tissue;
combination, composite, synthesis, fusion, aggregation
1.1A group of similar buildings or facilities on the same site: a leisure complex a complex of hotels
More example sentences
  • He has watched as new building complexes have risen over sites he knows contain more lost tombstones.
  • Dentists' offices, doctors' offices and markets were all built into the apartment complexes to make life more efficient.
  • About 70 families were left homeless by the fire, which destroyed three buildings in the apartment complex.
2 Psychoanalysis A related group of repressed or partly repressed emotionally significant ideas which cause psychic conflict leading to abnormal mental states or behaviour.
Example sentences
  • For about six to eight hours you seem to have no physical experience of the chronic muscular tensions that Reich says are symptomatic of unhealthy mental or emotional complexes.
  • Jung, Freud and comrades helped to systematise intuitive skill while deciphering some psychic complexes of their own Europe in turmoil.
  • Like Jack, David had a complex and conflicted history of diagnoses, treatments and medication.
2.1 informal A strong or disproportionate concern or anxiety about something: there’s no point having a complex about losing your hair
More example sentences
  • I had such a complex about it that I never noticed that I was actually quite fair compared to everyone in the class.
  • He was also a bookworm who had a complex about his family's poverty and a fan of kung fu and violent movies.
  • Perhaps I should get a complex about the Jonah joke.
French idée fixe
informal hang-up, thing, bee in one's bonnet
3 Chemistry An ion or molecule in which one or more groups are linked to a metal atom by coordinate bonds: two guanine bases can attach themselves to the same platinum atom, forming a stable complex
More example sentences
  • It is known that metal cations form complexes with anionic phosphodiester groups and carbonyl oxygens in the glycerol backbone of phosphocholine lipids.
  • It correctly accounts for the structures of most covalent compounds of elements other than transition metal complexes.
  • If two molecules or complexes have the same molecular formula they are candidates for stereochemical analysis.
3.1Any loosely bonded species formed by the association of two molecules: cross-linked protein-DNA complexes
More example sentences
  • This might occur in newly synthesized proteins to aid in folding or in mature proteins to control their activity or association with other protein complexes.
  • The chromo-domain and the related chromo-shadow domain mediate the formation of protein complexes and their association with chromatin.
  • It is not, however, clear whether association of ternary complexes is necessary to confer photoactivity, for instance by a stabilization effect.


[with object] Chemistry
Make (an atom or compound) form a complex with another: the DNA was complexed with the nuclear extract
More example sentences
  • Chloride is complexed with the silver chromate and fixed in a circular pattern around the entry point.
  • They may reduce mineral metal ions through direct contact or by reducing complexed ions.
  • Iron is mostly complexed with the organic ligands or colloids that are very abundant in natural seawater.



noun ( Chemistry )
Example sentences
  • The resulting NTA surface is activated by complexation of Cu 2 + ions rendering it capable of reversible immobilization of His-tagged proteins.
  • These results can be understood on the basis of preferential complexation of PicoGreen with base paired structures assumed by DNA following both intramolecular and intermolecular aggregation.
  • In our analysis of complexation of lipids via water bridging, we do not distinguish between the two types of hydrogen-bonded interactions between cholesterol and water, placing them both in the general binding mode category, WB.


Example sentences
  • As it is, the somewhat uniform and monolithic representation of ‘the West’ mars the attempt to produce a nuanced and subtle reading of cultural hybridity as the inevitable product of a complexly interwoven global milieu.
  • In contradiction to the usual concept of poetry as dense and academic, complexly layered with meaning and allusion, McGarragle is hoping to hook audiences with ‘in-between’ poetry.
  • Modern fathers are complex - and they have to be complexly, not crudely, managed to get the best out of them.


Mid 17th century (in the sense 'group of related elements'): from Latin complexus, past participle (used as a noun) of complectere 'embrace, comprise', later associated with complexus 'plaited'; the adjective is partly via French complexe.

For editors and proofreaders

Line breaks: com|plex

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