Evolutionary describes something that changes gradually over a very long time, developing step by step rather than all at once. The word comes from evolution, which means slow, steady change and development.

In biology, evolutionary changes happen across generations of living things. Birds didn't suddenly appear with wings one day. Instead, over millions of years, small changes in each generation eventually led to the birds we see today. Scientists study these evolutionary patterns to understand how different species developed their unique features.

The word also describes gradual change in other areas. A company might take an evolutionary approach to improving its products, making small improvements each year rather than completely redesigning everything overnight. A writer's style might show evolutionary development, getting better and more sophisticated with each book.

The opposite would be revolutionary, which means sudden, dramatic change. Think of the difference this way: learning to ride a bike with training wheels, then without, then trying tricks is evolutionary. Jumping from never riding to performing in a cycling competition would be revolutionary (and probably impossible!).