1.  involution(n = noun.process) - reduction in size of an organ or part (as in the return of the uterus to normal size after childbirth);
is a kind of biological process, organic process

2.  involution(n = noun.communication) - a long and intricate and complicated grammatical construction;
is a kind of construction, expression, grammatical construction

3.  involution(n = noun.attribute) elaborateness, elaboration, intricacy - marked by elaborately complex detail;
is a kind of complexity, complexness

4.  involution(n = noun.act) engagement, involvement, participation - the act of sharing in the activities of a group; "the teacher tried to increase his students' engagement in class activities"
is a kind of group action
has particulars: commitment, intercession, intervention, group participation
Derived form verb involve₂

5.  involution(n = noun.act) exponentiation - the process of raising a quantity to some assigned power;
is a kind of mathematical operation, mathematical process, operation

6.  involution(n = noun.act) enfolding - the action of enfolding something;
is a kind of change of shape

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." [1913 Webster]

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

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

involution, 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).

Derivative:
involutional adj.

Etymology:
L involutio (as INVOLVE)

N  obscurity, involution, hard words, ambiguity, unintelligibleness, vagueness &c, inexactness, what d'ye call 'em, darkness of meaning, obscure, crabbed, involved, confused.

N  complexity, complexness, complexus, complication, implication, intricacy, intrication, perplexity, network, labyrinth, wilderness, jungle, involution, raveling, entanglement, coil, sleave, tangled skein, knot, Gordian knot, wheels within wheels, kink, gnarl, knarl, webwork, difficulty, gnarled, knarled, complex, complexed, intricate, complicated, perplexed, involved, raveled, entangled, knotted, tangled, inextricable, irreducible.

N  numeration, numbering, pagination, tale, recension, enumeration, summation, reckoning, computation, supputation, calculation, calculus, algorithm, algorism, rhabdology, dactylonomy, measurement, statistics, arithmetic, analysis, algebra, geometry, analytical geometry, fluxions, differential calculus, integral calculus, infinitesimal calculus, calculus of differences, dead reckoning, muster, poll, census, capitation, roll call, recapitulation, account, notation, addition, subtraction, multiplication, division, rule of three, practice, equations, extraction of roots, reduction, involution, evolution, estimation, approximation, interpolation, differentiation, integration, abacus, logometer, slide rule, slipstick, tallies, Napier's bones, calculating machine, difference engine, suan- pan, adding machine, cash register, electronic calculator, calculator, computer, arithmetician, calculator, abacist, algebraist, mathematician, statistician, geometer, programmer, accountant, auditor, numeral, numerical, arithmetical, analytic, algebraic, statistical, numerable, computable, calculable, commensurable, commensurate, incommensurable, incommensurate, innumerable, unfathomable, infinite, quantitatively, arithmetically, measurably, in numbers.

N  convolution, winding, convolution, involution, circumvolution, wave, undulation, tortuosity, anfractuosity, sinuosity, sinuation, meandering, circuit, circumbendibus, twist, twirl, windings and turnings, ambages, torsion, inosculation, reticulation, rivulation, roughness, coil, roll, curl, buckle, spiral, helix, corkscrew, worm, volute, rundle, tendril, scollop, scallop, escalop, kink, ammonite, snakestone, serpent, eel, maze, labyrinth, knot, convoluted, winding, twisted, tortile, tortive, wavy, undated, undulatory, circling, snaky, snake-like, serpentine, serpent, anguill, vermiform, vermicular, mazy, tortuous, sinuous, flexuous, anfractuous, reclivate, rivulose, scolecoid, sigmoid, sigmoidal, spiriferous, spiroid, involved, intricate, complicated, perplexed, labyrinth, labyrinthic, labyrinthian, labyrinthine, peristaltic, daedalian, kinky, knotted, wreathy, frizzly, crepe, buckled, raveled, spiral, coiled, helical, cochleate, cochleous, screw-shaped, turbinated, turbiniform, in and out, round and round, a can of worms, Gordian knot.