intergradation

[in-ter-grey-dey-shuh n]
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noun

the act or process of intergrading or the state of being intergraded.
an evolutionary process by which different species of organisms tend to merge through a series of intermediate stages or grades.

Origin of intergradation

First recorded in 1870–75; inter- + gradation
Related formsin·ter·gra·da·tion·al, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for intergradation

Historical Examples of intergradation