introgression

US: (in′trə gresh′ən)

WordReference Random House Unabridged Dictionary of American English © 2026

in•tro•gres•sion  (in′trə gresh′ən), n. [Genetics.]

the introduction of genes from one species into the gene pool of another species, occurring when matings between the two produce fertile hybrids. Also called in•tro•gres′sive hybridiza′tion  (in′trə gres′iv). 
• Latin intrōgress(us), past participle of intrōgredī to go in, enter (intrō- intro- + -gred-, combining form of grad(ī) to proceed, walk + -tus past participle suffix, with -dt- -ss-) + -ion
• 1930–35 (earlier in literal sense of Latin)