reversion

1. The manifestation in an individual of certain characteristics, peculiar to a remote ancestor, which have been suppressed during one or more of the intermediate generations. 2. The return to the original phenotype, either by reinstatement of the original genotype (true r.) or by a mutation at a site different from that of the first mutation, which cancels the effect of the first mutation (suppressor mutation). [L. reversio (see reversal)]

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re·ver·sion ri-'vər-zhən, -shən n

1 a) an act or the process of returning (as to a former condition)

b) a return toward an ancestral type or condition: reappearance of an ancestral character

2) a product of reversion specif an organism with an atavistic character

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re·ver·sion (re-vurґzhən) [re- + version] 1. regression (def. 1). 2. in genetics, the mutation of a mutant phenotype so that the original function is restored; the term can be used specifically to denote mutation of the DNA such that the parental base sequence is regained (reverse mutation), but can be also be used more broadly to describe production of an altered base sequence that nevertheless encodes the original amino acid or masking of the first alteration by a second via suppression (q.v.).