complex

definition: 
complicated in structure; consisting of interconnected parts; difficult to understand or explain
sentence: 
Scientists also want to understand how de novo genes get incorporated into the complex network of reactions that drive the cell, a particularly puzzling problem.
Their efforts to douse the flames had failed, but they had just survived a huge explosion at the warehouse complex.
difficulty: 
very easy
toefl frequency: 
2
toefl classification: