A design contradiction consists of a design incompatibility between two or more design parameters.

For example, a parachute gives a speed related design contradiction. The contradiction exists between the desire to reduce the speed of descent of a parachute versus the amount of parachute area required to achieve the speed reduction. In other words, the parachute designer is only able to improve (reduce) descent speed by worsening (using more) parachute material. (Example excerpted from “Creativity As An Exact (Biomimetic) Science“)