involution

(noun) reduction in size of an organ or part (as in the return of the uterus to normal size after childbirth).

(noun) a long and intricate and complicated grammatical construction.

(noun) marked by elaborately complex detail. Synonyms: elaborateness, elaboration, intricacy.

(noun) the act of sharing in the activities of a group. Synonyms: engagement, participation, involvement. Example: "The teacher tried to increase his students' engagement in class activities."

(noun) the process of raising a quantity to some assigned power. Synonyms: exponentiation.

(noun) the action of enfolding something. Synonyms: enfolding.