in·vag·i·na·tion noun \-ˌvaj-ə-ˈnā-shən\
: an act or process of invaginating: as a : the formation of a gastrula by an infolding of part of the wall of the blastula b : intestinal intussusception
Seen & Heard
What made you want to look up invagination? Please tell us where you read or heard it (including the quote, if possible).