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The Collaborative International Dictionary of English v.0.48 (gcide)

mutation \mu*ta"tion\ (m[-u]*t[=a]"sh[u^]n), n. [L. mutatio, fr.
mutare to change: cf. F. mutation. See {Mutable}.]
Change; alteration, either in form or qualities.
[1913 Webster]

The vicissitude or mutations in the superior globe are
no fit matter for this present argument. --Bacon.
[1913 Webster]

2. (Biol.) Gradual definitely tending variation, such as may
be observed in a group of organisms in the fossils of
successive geological levels.
[Webster 1913 Suppl.]

3. (Biol.)
(a) As now employed (first by de Vries), a cellular
process resulting in a sudden inheritable variation
(the offspring differing from its parents in some
well-marked character or characters) as distinguished
from a gradual variation in which the new characters
become fully developed only in the course of many
generations. The occurrence of mutations, the
selection of strains carrying mutations permitting
enhanced survival under prevailing conditions, and the
mechanism of hereditary of the characters so
appearing, are well-established facts; whether and to
what extent the mutation process has played the most
important part in the evolution of the existing
species and other groups of organisms is an unresolved
question.
(b) The result of the above process; a suddenly produced
variation.

Note: Mutations can occur by a change in the fundamental
coding sequence of the hereditary material, which in
most organisms is DNA, but in some viruses is RNA. It
can also occur by rearrangement of an organism's
chromosomes. Specific mutations due to a change in DNA
sequence have been recognized as causing certain
specific hereditary diseases. Certain processes which
produce variation in the genotype of an organism, such
as sexual mixing of chromosomes in offspring, or
artificially induced recombination or introduction of
novel genetic material into an organism, are not
referred to as mutation.
[Webster 1913 Suppl. PJC]

4. (Biol.) a variant strain of an organism in which the
hereditary variant property is caused by a mutation[3].
[Webster 1913 Suppl.]