Entanglement; a spiralling inwards; intricacy.

A complicated grammatical construction.

(mathematics) An endofunction whose square is equal to the identity function; a function equal to its inverse.

(medicine) The shrinking of an organ (such as the uterus) to a former size.

(physiology) The regressive changes in the body occurring with old age.

(economics, social sciences, of a society or nation) A cessation of development or progress despite intense inner competition.

(neologism, slang) A state of increased competition for limited resources, requiring great effort to stay ahead.