n.1 the process of involving.
2 an entanglement.
3 intricacy.
4 curling inwards.
5 a part that curls upwards.
6 Math. the raising of a quantity to any power.
7 Physiol. the reduction in size of an organ in old age, or when its purpose has been fulfilled (esp. the uterus after childbirth).
Derivatives:
involutional adj.
Etymology: L involutio (as INVOLVE)