Definition of "Complex" :

noun: a whole structure (as a building) made up of interconnected or related structures

noun: a conceptual whole made up of complicated and related parts

"The complex of shopping malls, houses, and roads created a new town."

noun: (psychoanalysis) a combination of emotions and impulses that have been rejected from awareness but still influence a person's behavior

noun: a compound described in terms of the central atom to which other atoms are bound or coordinated

adjective: complicated in structure; consisting of interconnected parts

"A complex set of variations based on a simple folk melody."

adjective: difficult to analyze or understand

"He's more complex than he seems on the surface."