1.  invagination(n = noun.state) introversion - the condition of being folded inward or sheathed;
is a kind of condition
Derived form verb invaginate₁

2.  invagination(n = noun.process) infolding, introversion, intussusception - the folding in of an outer layer so as to form a pocket in the surface; "the invagination of the blastula"
is a kind of biological process, organic process
Derived form verb invaginate₂

1.  The condition of an invaginated organ or part. [1913 Webster]

2.  The inward movement of the wall of a tissue or cell, to form a cavity; also, the cavity thus formed. [PJC]

3.  The inward movement of one part of the wall of a blastula, to form a gastrula; the process of gastrulation, in which layers of the ovum are differentiated. [1913 Webster]
" In embolic invagination, one half of the blastosphere is pushed in towards the other half, producing an embryonic form known as a gastrula. -- In epibolic invagination, a phenomenon in the development of some invertebrate ova, the epiblast appears to grow over or around the hypoblast." [1913 Webster]

N  organization, organized world, organized nature, living nature, animated nature, living beings, organic remains, fossils, protoplasm, cytoplasm, protein, albumen, structure, organization, organism, biology, natural history, organic chemistry, anatomy, physiology, zoology, botany, microbiology, virology, bacteriology, mycology, naturalist, archegenesis, antherozoid, bioplasm, biotaxy, chromosome, dysmeromorph, ecology, oecology, erythroblast, gametangium, gamete, germinal matter, invagination, isogamy, oogamy, karyaster, macrogamete, microgamete, metabolism, anabolism, catabolism, metaplasm, ontogeny, ovary, ovum, oxidation, phylogeny, polymorphism, protozoa, spermary, spermatozoon, trophoplasm, vacuole, vertebration, zoogloea, zygote, Darwinism, neo-Darwinism, Lamarkism, neoLamarkism, Weismannism, morphology, taxonomy, organic, organized, karyoplasmic, unsegmentic, vacuolar, zoogloeic, zoogloeoid.