%involution%

n. [ L. involutio: cf. F. involution. See Involve. ] [ 1913 Webster ]

1. The act of involving or infolding. [ 1913 Webster ]

2. The state of being entangled or involved; complication; entanglement. [ 1913 Webster ]

All things are mixed, and causes blended, by mutual involutions. Glanvill. [ 1913 Webster ]

3. That in which anything is involved, folded, or wrapped; envelope. Sir T. Browne. [ 1913 Webster ]

4. (Gram.) The insertion of one or more clauses between the subject and the verb, in a way that involves or complicates the construction. [ 1913 Webster ]

5. (Math.) The act or process of raising a quantity to any power assigned; the multiplication of a quantity into itself a given number of times; -- the reverse of evolution. [ 1913 Webster ]

6. (Geom.) The relation which exists between three or more sets of points, a.a′, b.b′, c.c′, so related to a point O on the line, that the product Oa.Oa′ = Ob.Ob′ = Oc.Oc′ is constant. Sets of lines or surfaces possessing corresponding properties may be in involution. [ 1913 Webster ]

7. (Med.) The return of an enlarged part or organ to its normal size, as of the uterus after pregnancy. [ 1913 Webster ]