Complex/kəmˈpleks,ˈkɑːmpleks/ Definition 1 of 5Pro Tip 1/3Abstract Concepts Often describes things you can't touch but must understand through thought like emotions. The concept of freedom is complex. Pro Tip 2/3Subjective Interpretation Can signal that different people might see situations differently, not clear cut. The poem's meaning is complex and varies with interpretation. Pro Tip 3/3Varied Usage Used across various disciplines to describe intricate systems or ideas. The ecosystem of the rainforest is complex.