Main Entry: in·tro·gres·sion

Pronunciation: \ˌin-trə-ˈgre-shən\

Function: noun

Etymology: intro- + -gression (as in regression)

Date: 1938

: the entry or introduction of a gene from one gene complex into another (as by hybridization)

— in·tro·gres·sant \-ˈgre-s^ənt\ adjective or noun

— in·tro·gres·sive \-ˈgre-siv\ adjective