Origin of complex

1645–55; 1905–10 for def 7; (adj.) < Latin complexus, past participle of complectī, complectere to embrace, encompass, include, equivalent to complect- (see complect) + -tus past participle suffix; (noun) < Late Latin complexus totality, complex (Latin: inclusion, grasping, embrace), equivalent to complect(ere) + -tus suffix of v. action; reanalysis of the Latin v. as “to intertwine (completely)” has influenced sense of the adj.
Related formscom·plex·ly, adverbcom·plex·ness, nouno·ver·com·plex, adjectivequa·si-com·plex, adjectivequa·si-com·plex·ly, adverbsu·per·com·plex, adjectiveun·com·plex, adjectiveun·com·plex·ly, adverbun·com·plex·ness, noun

Synonyms for complex

Antonyms for complex

2, 3. simple.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for complex

Contemporary Examples of complex

Historical Examples of complex

British Dictionary definitions for complex



made up of various interconnected parts; composite
(of thoughts, writing, etc) intricate or involved
  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
maths of or involving one or more complex numbers


a whole made up of interconnected or related partsa building complex
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
informal an obsession or excessive fearhe's got a complex about cats
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
any chemical compound in which one molecule is linked to another by a coordinate bond
Derived Formscomplexly, adverbcomplexness, noun

Word Origin for complex

C17: from Latin complexus, from complectī to entwine, from com- together + plectere to braid


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
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for complex

1650s, "composed of parts," from French complexe "complicated, complex, intricate" (17c.), from Latin complexus "surrounding, encompassing," past participle of complecti "to encircle, embrace," in transferred use, "to hold fast, master, comprehend," from com- "with" (see com-) + plectere "to weave, braid, twine, entwine," from PIE *plek-to-, from root *plek- "to plait" (see ply (v.1)). The meaning "not easily analyzed" is first recorded 1715. Complex sentence is attested from 1881.


1650s, "a whole comprised of parts," from complex (adj.). Psychological sense of "connected group of repressed ideas" was established by C.G. Jung, 1907.

Online Etymology Dictionary, © 2010 Douglas Harper

complex in Medicine




A group of related, often repressed memories, thoughts, and impulses that compel characteristic or habitual patterns of feelings, thought, and behavior.
The relatively stable combination of two or more ions or compounds into a larger structure without covalent binding.
A composite of chemical or immunological structures.
An entity made up of three or more interrelated components.
A group of individual structures known or believed to be anatomically, embryologically, or physiologically related.
The combination of factors, symptoms, or signs that forms a syndrome.


Consisting of interconnected or interwoven parts; composite.
Composed of two or more units.
Relating to a group of individual structures known or considered to be anatomically, embryologically, or physiologically related.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.