Trivia Time

Which psychologist popularized the modern psychological concept of a complex?

Test Your Knowledge

complex

American  

[kuhm-pleks, kom-pleks, kom-pleks] / kəmˈplɛks, ˈkɒm plɛks, ˈkɒm plɛks /

adjective

1. composed of many interconnected parts; compound; composite.

   a complex highway system.

2. characterized by a very complicated or involved arrangement of parts, units, etc..

   complex machinery.

   Antonyms:

   simple

3. so complicated or intricate as to be hard to understand or deal with.

   a complex problem.

   Synonyms:

   labyrinthine, tangled, knotty

   Antonyms:

   simple

4. Grammar.

   1. (of a word) consisting of two parts, at least one of which is a bound form, as childish, which consists of the word child and the bound form -ish.

   2. complex sentence.

5. Mathematics. pertaining to or using complex numbers.

   complex methods; complex vector space.

---

noun

• complexes
  plural

1. an intricate or complicated association or assemblage of related things, parts, units, etc..

   the entire complex of our educational system; an apartment complex.

   Synonyms:

   labyrinth, tangle, web, network

2. Psychology. a system of interrelated, emotion-charged ideas, feelings, memories, and impulses that is usually repressed and that gives rise to abnormal or pathological behavior.

3. a fixed idea; an obsessive notion.

4. Mathematics.

   1. an arbitrary set of elements of a group.

   2. a collection of simplexes having specified properties.

5. Also called coordination compound. Chemistry. a compound in which independently existing molecules or ions of a nonmetal complexing agent form coordinate bonds with a metal atom or ion.

6. Biochemistry. an entity composed of molecules in which the constituents maintain much of their chemical identity.

   receptor-hormone complex, enzyme-substrate complex.

verb (used with object)

1. Chemistry. to form a complex with.

verb (used without object)

1. Chemistry. to form a complex.

complex British  

/ ˈkɒmplɛks /

adjective

1. made up of various interconnected parts; composite

2. (of thoughts, writing, etc) intricate or involved

3. grammar

   1. (of a word) containing at least one bound form

   2. (of a noun phrase) containing both a lexical noun and an embedded clause, as for example the italicized parts of the following sentence: I didn't know the man who served me

   3. (of a sentence) formed by subordination of one clause to another

4. maths of or involving one or more complex numbers

---

noun

1. a whole made up of interconnected or related parts

   a building complex

2. psychoanal a group of emotional ideas or impulses that have been banished from the conscious mind but that continue to influence a person's behaviour

3. informal an obsession or excessive fear

   he's got a complex about cats

4. Also called: coordination compound. a chemical compound in which molecules, groups, or ions are attached to a central metal atom, esp a transition metal atom, by coordinate bonds

5. any chemical compound in which one molecule is linked to another by a coordinate bond

Usage

Complex is sometimes wrongly used where complicated is meant. Complex is properly used to say only that something consists of several parts. It should not be used to say that, because something consists of many parts, it is difficult to understand or analyse

Other Word Forms

Derived Forms

• complexness
  noun
• uncomplexness
  noun
• overcomplex
  adjective
• quasi-complex
  adjective
• supercomplex
  adjective
• uncomplex
  adjective
• complexly
  adverb
• quasi-complexly
  adverb
• uncomplexly
  adverb

Inflected Forms

Nouns

• complexes
  plural

---

Etymology

Origin of complex

First recorded in 1645–55; 1905–10 complex for def. 7; adjective from Latin complexus, past participle of complectī, complectere “to embrace, encompass, include,” equivalent to complect- ( see complect) + -tus past participle suffix; noun from Late Latin complexus “totality, complex” ( Latin: “inclusion, grasping, embrace”), equivalent to complect(ere) + -tus suffix of verb action; reanalysis of the Latin verb as “to intertwine (completely)” influenced sense of the adjective

---

Explanation

People who are really good at math can handle complex math problems. The rest of us are all set with simple stuff like the times tables. Use complex to refer to something that is not simple. Something complex has two or more related parts, or is not simple in its structure. As a noun, a complex is a group of units, often a group of buildings. The adjective is stressed on the second syllable, but the noun is stressed on the first syllable. Complex is from Latin complexus, from complecti "to encircle or embrace."

Example Sentences

See Examples For:

complex complexes

Veterans Stadium in Long Beach is set for demolition to build a modern sports complex.

From Los Angeles Times ● Oct. 16, 2026

The researchers selected this environment because its microorganisms already possess the biological machinery needed to break down complex natural materials.

From Science Daily ● Oct. 16, 2026

But fitting dozens of motors and sensors into a human-shaped metal frame is a complex and expensive engineering challenge.

From MarketWatch ● Oct. 16, 2026

He was discharged with a complex postsurgery medication regimen to keep his immune system in check and prevent infection, one that had to be followed perfectly.

From Slate ● Oct. 16, 2026

The game is so complex, with more possible combinations of moves than there are atoms in the known universe, there’s an exception to every rule.

From "Fallout: Spies, Superbombs, and the Ultimate Cold War Showdown" by Steve Sheinkin

The state also hosts the nation’s premier national-security launch complexes up and down the Space Coast along the Atlantic in Central Florida.

From The Wall Street Journal ● Sep. 10, 2026

Up to now, this area has barely been studied in comparison with famous nearby sites such as the Valley of the Kings and the large temple complexes of Luxor and Karnak.

From Science Daily ● Sep. 10, 2026

On Friday, lawmakers agreed on a compromise on proposed legislation to regulate energy use by California’s growing data center industry, measures prompted by community fears about the massive complexes.

From Los Angeles Times ● Sep. 1, 2026

SpaceX’s new spaceport will be the largest in the world, with five launch complexes, each equipped with two pads.

From MarketWatch ● Aug. 25, 2026

Soon word spread to the parking lots and apartment complexes around town.

From "Outcasts United: An American Town, a Refugee Team, and One Woman's Quest to Make a Difference" by Warren St. John

Random Word

Spin the wheel and learn a new word!

---

Related Words

• complicated
• convoluted
• disturbing
• intricate
• obscure
• perplexing
• sophisticated

---