A description of the state of being ill beyond the hope of recovery, with death imminent.

An individual who is so seriously ill as to be dying is said to be in extremis.

West's Encyclopedia of American Law, edition 2. Copyright 2008 The Gale Group, Inc. All rights reserved.

EXTREMIS. When a person is sick beyond the hope of recovery, and near death, he is said to be in extremism.
     2. A will made in this condition, if made without undue influence, by a person of sound mind, is valid.
     3. The declarations of persons in extremis, when made with a full consciousness of approaching death, ate admissible in evidence when the death of the person making them is the subject of the charge, and the circumstances of the death the subject of such declarations. 2 B. & C. 605 S. C. 9 Eng. C. L. Rep..196; and see 15 John. 286; 1 John. Rep. 159; 2 John. R. 31; 7 John. 95; 2 Car. Law. Repos. 102; 5 whart, R. 396-7.

A Law Dictionary, Adapted to the Constitution and Laws of the United States. By John Bouvier. Published 1856.
References in classic literature ?
The Lovell Mingotts' dinner, patched up in extremis out of all sorts of social odds and ends, ought to have taught her the narrowness of her escape; but either she had been all along unaware of having skirted disaster, or else she had lost sight of it in the triumph of the van der Luyden evening.
This object led a sort of "in extremis" existence in a wooden box placed against the starboard mooring-bitts, tended and nursed with the greatest sympathy and care by all the children, who greatly enjoyed pulling long faces and moving with hushed footsteps.
The book has been produced by Stirling-based Extremis Publishing.
Which is why, in extremis, our port of call, always, is 999 and, yup, our NHS.
A portrait of Marie Colvin in the living room at the family home in East Norwich, New York Image Credit: NYT In Extremis: The Life and Death of the War Correspondent
Written by fellow foreign correspondent Lindsey Hilsum, In Extremis is the story of the most daring war reporter of her age.
Por esta relacion extrema fundada en el no transcurrir hablamos pues de un aburrido in extremis.
Gannon's Oblivion (9781481483254, $16.00) joins the prequel Extremis and takes place after the war with the alien Arduans has ended.
They expressed their regret that the Swedish government keeps a neutral stance towards what is going on in Syria as the extremis thinking is spreading in Europe in an accelerated manner.