Symptoms of poor design

1. Rigidity — The design is hard to change.
2. Fragility — The design is easy to break.
3. Immobility — The design is hard to reuse.
4. Viscosity — It is hard to do the right thing.
5. Needless Complexity — Overdesign.
6. Needless Repetition — Mouse abuse.
7. Opacity — Disorganized expression.

These symptoms are similar in nature to code smells, but they are at a higher level. They are smells that pervade the overall structure of the software rather than a small section of code.

Robert C. Martin, "Agile Design", in Agile Software Development:
Principles, Patterns, and Practices, 85.