Pronunciation: (in"vu-lOO'shun),[key] —n. 1. an act or instance of involving or entangling; involvement.
2. the state of being involved.
3. something complicated.
4. Bot.,Zool. a. a rolling up or folding in upon itself.
b. a part so formed.
5. Biol.retrograde development; degeneration.
6. Physiol.the regressive changes in the body occurring with old age.
7. Gram.a complex construction in which the subject is separated from its predicate by intervening clauses or phrases.
8. Math.a function that is its own inverse.