What is Complex ?
Complex is (adj) complicated The committee is discussing the complex problem of the site for the new hospital. The specifications for the machine are very complex.(noun) 1. a series of buildings The council has built a new sports complex. An industrial complex is planned on the site of the old steel works. 2. (in psychiatry) a group of ideas which are based on an experience that you had in the past, and which influence the way you behave He has a complex about going bald. Stop talking about her height – you’ll give her a complex about it.
source: Easier English, Student Dictionary Upper Intermediate Level