A term borrowed from engineering indicating failure to realize an “ideal” design because improving performance in one area entails decreasing performance in another area or because of another constraint on the design. Sometimes this term is applied to biological features even though these traits evolved and were not designed. In terms of evolution, a “design” compromise indicates a constraint or trade-off during a feature’s evolution. For more details, read about why evolved traits may not be perfectly “engineered” in Evolution 101.