olemus
(1) matemaatikas
teisendus, mis ühtub oma pöördteisendusega
Wiktionary:
3. (mathematics) a function equal to its inverse
https://en.wikipedia.org/wiki/Involution_(mathematics)
https://encyclopediaofmath.org/wiki/Involution

(2) bioloogias
taandardeng
Dictionary.com:
6. (biology) retrograde development; degeneration

(3) füsioloogias
elundi suuruse ennistumine
Wiktionary:
4. (medicine) the shrinking of an organ (such as the uterus) to a former size
https://en.wikipedia.org/wiki/Involution_(medicine)