evolution
noun evo·lu·tion \ˌe-və-ˈlü-shən, ˌē-və-\
biology : a theory that the differences between modern plants and animals are because of changes that happened by a natural process over a very long time
: the process by which changes in plants and animals happen over time
: a process of slow change and development
Full Definition of EVOLUTION
b : the action or an instance of forming and giving something off : emission
c (1) : a process of continuous change from a lower, simpler, or worse to a higher, more complex, or better state : growth
d : something evolved
b : a theory that the various types of animals and plants have their origin in other preexisting types and that the distinguishable differences are due to modifications in successive generations;also : the process described by this theory