[ ev-uh-loo-shuhn or, esp. British, ee-vuh- ]
/ ˌɛv əˈlu ʃən or, esp. British, ˌi və- /


Origin of evolution

1615–25; < Latin ēvolūtiōn- (stem of ēvolūtiō) an unrolling, opening, equivalent to ēvolūt(us) (see evolute) + -iōn- -ion


Example sentences from the Web for evolution

British Dictionary definitions for evolution

/ (ˌiːvəˈluːʃən) /


biology a gradual change in the characteristics of a population of animals or plants over successive generations: accounts for the origin of existing species from ancestors unlike them See also natural selection
a gradual development, esp to a more complex form the evolution of modern art
the act of throwing off, as heat, gas, vapour, etc
a pattern formed by a series of movements or something similar
an algebraic operation in which the root of a number, expression, etc, is extracted Compare involution (def. 6)
military an exercise carried out in accordance with a set procedure or plan

Derived forms of evolution

evolutionary or evolutional, adjective

Word Origin for evolution

C17: from Latin ēvolūtiō an unrolling, from ēvolvere to evolve

Medical definitions for evolution

[ ĕv′ə-lōōshən, ē′və- ]


A continuing process of change from one state or condition to another or from one form to another.
The theory that groups of organisms change with passage of time, mainly as a result of natural selection, so that descendants differ morphologically and physiologically from their ancestors.

Scientific definitions for evolution

[ ĕv′ə-lōōshən ]

The process by which species of organisms arise from earlier life forms and undergo change over time through natural selection. The modern understanding of the origins of species is based on the theories of Charles Darwin combined with a modern knowledge of genetics based on the work of Gregor Mendel. Darwin observed there is a certain amount of variation of traits or characteristics among the different individuals belonging to a population. Some of these traits confer fitness-they allow the individual organism that possesses them to survive in their environment better than other individuals who do not possess them and to leave more offspring. The offspring then inherit the beneficial traits, and over time the adaptive trait spreads through the population. In twentieth century, the development of the the science of genetics helped explain the origin of the variation of the traits between individual organisms and the way in which they are passed from generation to generation. This basic model of evolution has since been further refined, and the role of genetic drift and sexual selection in the evolution of populations has been recognized. See also natural selection sexual selection. See Notes at adaptation Darwin.
A process of development and change from one state to another, as of the universe in its development through time.

A Closer Look

Darwin's theory of evolution by natural selection assumed that tiny adaptations occur in organisms constantly over millions of years. Gradually, a new species develops that is distinct from its ancestors. In the 1970s, however, biologists Niles Eldredge and Stephen Jay Gould proposed that evolution by natural selection may not have been such a smooth and consistent process. Based on fossils from around the world that showed the abrupt appearance of new species, Eldredge and Gould suggested that evolution is better described through punctuated equilibrium. That is, for long periods of time species remain virtually unchanged, not even gradually adapting. They are in equilibrium, in balance with the environment. But when confronted with environmental challenges-sudden climate change, for example-organisms adapt quite quickly, perhaps in only a few thousand years. These active periods are punctuations, after which a new equilibrium exists and species remain stable until the next punctuation.

Cultural definitions for evolution


A theory first proposed in the nineteenth century by Charles Darwin, according to which the Earth's species have changed and diversified through time under the influence of natural selection. Life on Earth is thought to have evolved in three stages. First came chemical evolution, in which organic molecules (see also organic molecule) were formed. This was followed by the development of single cells capable of reproducing themselves. This stage led to the development of complex organisms capable of sexual reproduction. Evolution is generally accepted as fact by scientists today, although debates continue over the precise mechanisms involved in the process. (See mutation, punctuated equilibrium, and creation science.)

notes for evolution

The first cell is thought to have been formed when the Earth was less than a billion years old.