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The English noun evolution (pronounced i//; from Latin ēvolūtiō "unfolding, unrolling") refers to any kind of accumulation of change, or gradual directional change. It is the 3,117th most commonly used word in English.
While the term primarily refers to biological evolution, there are various types of chemical evolution and it is also found in economics, historical linguistics, and many other technical fields where systems develop or change gradually over time, e.g. stellar evolution, cultural evolution, the evolution of an idea, metaphysical evolution, spiritual evolution, etc.
The English term prior to the late 19th century was confined to referring to goal-directed, pre-programmed processes such as embryological development. A pre-programmed task, as in a military maneuver, using this definition, may be termed an "evolution."
The term evolution (from its literal meaning of "unfolding" of something into its true or explicit form) carries a connotation of gradual improvement or directionality from a beginning to an end point. This contrasts with the more general development, which can indicate change in any direction, or revolution, which implies recurring, periodic change. The term biological devolution is coined as an antonym to evolution, indicating such degeneration or decrease in quality or complexity.