/ ˌiːvəˈluːʃn; NAmE ; ˌev-/ noun [ U ]
1.
( biology ) the gradual development of plants, animals, etc. over many years as they adapt to changes in their environment :
the evolution of the human species
Darwin's theory of evolution
2.
the gradual development of sth :
In politics Britain has preferred evolution to revolution (= gradual development to sudden violent change) .
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WORD ORIGIN
early 17th cent.: from Latin evolutio(n-) unrolling, from the verb evolvere , from e- (variant of ex- ) out of + volvere to roll. Early senses related to movement, first recorded in describing a “wheeling” manoeuvre in the realignment of troops or ships. Current senses stem from a notion of “opening out”, giving rise to the sense development .