introversion

noun

1.
the condition of being folded inward or sheathed
invagination
Derived from:
introvert
2.
the folding in of an outer layer so as to form a pocket in the surface
infolding intussusception invagination
Derived from:
introvert
3.
(psychology) an introverted disposition; concern with one's own thoughts and feelings
Antonym:
ambiversion extraversion
Derived from:
introvert