complex

noun
com·​plex | \ ˈkäm-ˌpleks \

Definition of complex

 (Entry 1 of 3)

1 : a whole made up of complicated or interrelated parts a complex of welfare programs the military-industrial complex
2a : a group of culture traits relating to a single activity (such as hunting), process (such as use of flint), or culture unit
b(1) : a group of repressed desires and memories that exerts a dominating influence upon the personality a guilt complex
(2) : an exaggerated reaction to or preoccupation with a subject or situation He has always had a complex about spiders. She has a weight complex. Not being able to find a job was giving me a complex.
c : a group of obviously related units of which the degree and nature of the relationship is imperfectly known
d : the sum of factors (such as symptoms) characterizing a disease or condition primary tuberculous complex
3 : a chemical association of two or more species (such as ions or molecules) joined usually by weak electrostatic bonds rather than covalent bonds
4 : a building or group of buildings housing related units an apartment complex a sports complex

complex

adjective
com·​plex | \ käm-ˈpleks , kəm-ˈpleks, ˈkäm-ˌpleks\

Definition of complex (Entry 2 of 3)

1a : composed of two or more parts : composite a complex mixture of chemicals
b(1) of a word : having a bound form as one or more of its immediate constituents Unmanly is a complex word.
(2) of a sentence : consisting of a main clause and one or more subordinate clauses
2 : hard to separate, analyze, or solve a complex problem
3 : of, concerned with, being, or containing complex numbers a complex root complex analysis

complex

verb
com·​plex | \ käm-ˈpleks , kəm-ˈpleks, ˈkäm-ˌpleks\
complexed; complexing; complexes

Definition of complex (Entry 3 of 3)

transitive verb

1 : to make complex or into a complex
2 : chelate

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Other Words from complex

Adjective

complexly adverb
complexness noun

Verb

complexation \ ˌkäm-​ˌplek-​ˈsā-​shən , kəm-​ \ noun

Choose the Right Synonym for complex

Adjective

complex, complicated, intricate, involved, knotty mean having confusingly interrelated parts. complex suggests the unavoidable result of a necessary combining and does not imply a fault or failure. a complex recipe complicated applies to what offers great difficulty in understanding, solving, or explaining. complicated legal procedures intricate suggests such interlacing of parts as to make it nearly impossible to follow or grasp them separately. an intricate web of deceit involved implies extreme complication and often disorder. a rambling, involved explanation knotty suggests complication and entanglement that make solution or understanding improbable. knotty ethical questions

The Complex Origins of Complex

The word complex lives up to its name, as it contains multiple parts of speech and senses. It serves as an adjective, a noun, and, less commonly, as a verb. The verb use is the oldest of the three, with an original meaning of “to join or unite.” Complex comes from the Latin complecti, which means “to entwine around, to embrace,” a word that is based in part on plectere (“to braid”). English has a number of other words that can be traced to plectere, including perplex, plexus (“an intricately interwoven combination of elements or parts in a cohering structure”), and amplexus (“the mating embrace of some amphibians, such as frogs and toads”).

Examples of complex in a Sentence

Noun

She has a complex about her appearance. a complex of protein molecules

Adjective

The house's wiring is complex. The situation is more complex than you realize.

Verb

there's no need to complex what should be a simple process for obtaining a building permit
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Recent Examples on the Web: Noun

This is a portrait of two complex, perhaps unlikeable women who are unapologetic in their ambition, but willfully blind as to what their ambitions truly aim for. Constance Grady, Vox, "The 16 best books I read in 2018," 21 Dec. 2018 Nary a month after opening and the massive complex, which occupies three solid blocks of Springfield’s downtown, is packed—with locals taking their first looks, tourists who never miss an MGM opening, and yes, gamblers. Andrea Bennett, Condé Nast Traveler, "Will New Casinos Bring a "MassVegas" to New England?," 17 Dec. 2018 The group was trapped by flooding after entering the complex on June 23, sparking a huge search and rescue operation led by the Thai military. Fox News, "Thailand cave rescue: Electronic location gear, breathing masks could help save soccer team," 2 Oct. 2018 Other residents at Village Square said Priestley was a relative newcomer to the complex, having moved in a little less than a year ago. Vinny Vella, Philly.com, "Bucks woman found dead after calling 911 to say boyfriend was going to kill her," 9 July 2018 Late last season, 50 masked intruders forced their way in to the complex and assaulted club employees. SI.com, "Ex-Sporting CP President Embroiled in €500,000 Per Year Communications Company Scandal," 10 July 2018 Police found footprints and handprints inside the complex, and other hikers cut off by floodwaters have been rescued from safe, higher ground inside the cave in the past, authorities said. Eli Meixler, Time, "Thai Divers Continue the Search For 12 Boys and Their Coach Trapped in a Flooded Cave. Here’s What to Know," 26 June 2018 The first 911 call came from someone at an apartment complex next to the school around 9 a.m. Tuesday. Jeffrey Collins, The Seattle Times, "School’s historical re-enactment causes shooting scare," 4 Dec. 2018 The amenities vary by community and builder, but some including AHV Communities load up their communities with everything expected from an apartment complex. Jeff Andrews, Curbed, "A brand new single-family neighborhood, where every unit is a rental," 10 Sep. 2018

Recent Examples on the Web: Adjective

Both of these accounts of these intense times were used to create Chalamet and Carrell's complex characters. Morgan Baila, refinery29.com, "Brace Yourselves For Timothée Chalamet & Steve Carrell In First Beautiful Boy Trailer," 27 June 2018 Bredesen crunched all these results with a computer algorithm that calculated a complex 36-point personalized therapeutic program to counteract Weinrich’s specific constellation of deficits. Linda Marsa, Discover Magazine, "A New Treatment for Alzheimer's? It Starts With Lifestyle," 16 Nov. 2018 In her op-ed for the New York Times, Recode Editor at Large Kara Swisher considers the complex ethical problems the tech industry faces and wonders if the solution is for companies to hire a chief ethics officer. Recode Staff, Recode, "Recode Daily: The Khashoggi crisis exposed an online intimidation campaign ordered by the Saudi Crown Prince," 22 Oct. 2018 Crypto mining is a process that involves solving complex mathematical problems to validate transactions made with digital currency such as Bitcoin, Litecoin, or Ethereum. Madeleine Rivera, Fox News, "Large-scale crypto mining operation launched in Lone Star State," 20 Aug. 2018 But many anti-Brexit lawmakers are clinging to hopes that the whole project could be abandoned as too complex or unworkable. NBC News, "Brexit chaos: What happens next for British PM Theresa May?," 10 July 2018 The Supreme Court has determined what affirmative action policies are constitutional, and the Court’s written decisions are the best guide for navigating this complex issue. Kathleen Megan, courant.com, "Two College Leaders Say Admissions Policies Won't Be Affected by Federal Roll-Back of Obama-Era Policies on Affirmative Action," 7 July 2018 The causes of these and the other major disasters of 2018 were complex, with many contributing factors. Umair Irfan, Vox, "What we learned from the disasters that hammered the US in 2018," 27 Dec. 2018 Her biggest project is Luma Arles, a 20-acre contemporary arts complex that includes a performance venue that launched last summer, and the crown jewel, a tower designed by Frank Gehry, which is slated to be completed in late 2019. Klara Glowczewska, Town & Country, "The Best Places to Travel in 2019," 7 Dec. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'complex.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of complex

Noun

1643, in the meaning defined at sense 1

Adjective

1645, in the meaning defined at sense 1a

Verb

1658, in the meaning defined at sense 1

History and Etymology for complex

Noun

Late Latin complexus totality, from Latin, embrace, from complecti — see complex entry 2

Adjective

Latin complexus, past participle of complecti to embrace, comprise (a multitude of objects), from com- + plectere to braid — more at ply

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Statistics for complex

Last Updated

9 Feb 2019

Look-up Popularity

Time Traveler for complex

The first known use of complex was in 1643

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More Definitions for complex

complex

noun

English Language Learners Definition of complex

 (Entry 1 of 2)

: a group of buildings, apartments, etc., that are located near each other and used for a particular purpose
: an emotional problem that causes someone to think or worry too much about something
: a group of things that are connected in complicated ways

complex

adjective

English Language Learners Definition of complex (Entry 2 of 2)

: having parts that connect or go together in complicated ways
: not easy to understand or explain : not simple
grammar : consisting of a main clause and one or more additional clauses

complex

adjective
com·​plex | \ käm-ˈpleks , kəm-ˈpleks, ˈkäm-ˌpleks\

Kids Definition of complex

1 : not easy to understand or explain : not simple complex instructions
2 : having parts that go together in complicated ways a complex invention

complex

adjective
com·​plex | \ käm-ˈpleks , kəm-ˈ , ˈkäm-ˌ\

Medical Definition of complex

 (Entry 1 of 3)

1 : having many varied interrelated parts, patterns, or elements and consequently hard to understand complex behavior a complex personality complex plants and animals
2 : formed by the union of simpler chemical substances complex proteins

complex

noun
com·​plex | \ ˈkäm-ˌpleks \

Medical Definition of complex (Entry 2 of 3)

1 : a group of repressed memories, desires, and ideas that exert a dominant influence on the personality and behavior a guilt complex — see castration complex, electra complex, inferiority complex, oedipus complex, persecution complex, superiority complex
2 : a group of chromosomes arranged or behaving in a particular way — see gene complex
3 : a chemical association of two or more species (as ions or molecules) joined usually by weak electrostatic bonds rather than by covalent bonds
4 : the sum of the factors (as symptoms and lesions) characterizing a disease primary tuberculous complex

complex

transitive verb
com·​plex | \ käm-ˈpleks , kəm-ˈ , ˈkäm-ˌ\

Medical Definition of complex (Entry 3 of 3)

1 : to form into a complex RNA complexed with protein
2 : chelate

intransitive verb

: to form a complex hormones which must complex with specific receptors

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Comments on complex

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