noun, plural: involutions
(1) (biology) Reverting of the uterus and other genital organs to the pre-pregnant size and state following childbirth.
(2) (embryology) The inward movement of an expanding outer layer of cells, thereby forming a dorsal lip in animal gastrulation.
(3) (physiology) The progressive, retrograding or degenerating changes in a senescing (aging) body; catagenesis.
(4) (medicine) Shrinking of an organ.
(5) (general) Turning or rolling inward; enfolding.
Word origin: Latin involutio, from volvere (to roll).
Related form(s): involute