complex

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Consisting of interconnected or interwoven parts; composite.
• adjective Composed of two or more units.
• adjective Difficult to understand for being intricate or involved; complicated.
• adjective Consisting of at least one bound form. Used of a word.
• adjective Consisting of an independent clause and at least one other independent or dependent clause. Used of a sentence.
• noun A whole composed of interconnected or interwoven parts.
• noun A building or group of buildings used for a single purpose.
• noun In psychology, a group of related, often repressed ideas and impulses that compel characteristic or habitual patterns of thought, feelings, and behavior. No longer in scientific use.
• noun An exaggerated or obsessive concern or fear.
• noun Medicine The combination of factors, symptoms, or signs of a disease or disorder that forms a syndrome.

from The Century Dictionary.

• noun Anything consisting in or formed by the union of interconnected parts; especially, an assemblage of particulars related as parts of a system.
• noun In geometry, a continuous, triply infinite system of infinite straight lines; the whole of any kind of forms in space fulfilling one condition: thus, all the lines that cut a given curve in space constitute a complex.
• To combine intricately; involve; mix up.
• Composed of interconnected parts; formed by a combination of simple things or elements; including two or more connected particulars; composite; not simple: as, a complex being; complex ideas; a complex term.
• Involved; intricate; complicated; perplexing.
• In the theory of numbers, any expression in the form ai + bj +, etc., where a, b, etc., are integers, and i, j, etc., are peculiar units.

from the GNU version of the Collaborative International Dictionary of English.

• noun Assemblage of related things; collection; complication.
• noun (Geom.) all the possible straight lines in space being considered, the entire system of lines which satisfy a single relation constitute a complex. The lines which satisfy two relations constitute a congruency of lines; as, the entire system of lines, each one of which meets two given surfaces, is a congruency.
• adjective Composed of two or more parts; composite; not simple.
• adjective Involving many parts; complicated; intricate.
• adjective See Fraction.
• adjective (Math.) in the theory of numbers, an expression of the form a + b√-1, when a and b are ordinary integers.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Made up of multiple parts; intricate or detailed.
• adjective Not simple or straightforward.
• adjective mathematics Of a number, of the form a + bi, where a and b are real numbers and i is the square root of −1.
• adjective geometry A curve, polygon or other figure that crosses or intersects itself.
• noun A problem.
• noun A collection of buildings with a common purpose, such as a university or military base.
• noun A psychologically based dislike or fear of a particular thing.
• noun A thunderstorm that forms when two storm fronts collide.
• noun chemistry A structure consisting of a central atom or molecule weakly connected to surrounding atoms or molecules.
• verb chemistry, intransitive To form a complex with another substance

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a conceptual whole made up of complicated and related parts
• noun a compound described in terms of the central atom to which other atoms are bound or coordinated
• noun a whole structure (as a building) made up of interconnected or related structures
• adjective complicated in structure; consisting of interconnected parts
• noun (psychoanalysis) a combination of emotions and impulses that have been rejected from awareness but still influence a person's behavior