Triage is the practice of sorting into prioritized groups. It is, perhaps, most commonly used in emergency and military medicine, where is the name of the process for evaluating mass casualties and assigning priority of treatment. In a typical triage, patients are sorted into three groups, those who get immediate treatment, those who can wait, and the expectant—those expected to die—who are treated last. The cold logic is that in a situation with mass casualties, precious resources cannot be wasted on those who will most likely die anyway.
Because of this medical practice of dividing patients into three groups, it is commonly thought that triage comes from tri- or three, the sorting into three categories. This is incorrect. Triage is a borrowing from the French, which in turn is from the verb trier, meaning to pick or to cull (which is also the source of the English verb to try). The use of triage in English dates to the 18th century. From Ephraim Chambers’ Cyclopædia, written between 1727-41:
Wool, Each fleece consists of wool of divers qualities, and degrees of fineness, which the dealers therein take care to separate...If the triage, or separation be well made, in 15 bales there will be [etc.].
The medical sense can be found from World War I. From a 27 December 1915[?] diary entry by a Tracy Putnam published in Mark Antony De Wolfe Howe’s 1916 The Harvard Volunteers in Europe: Personal Records of Experience in Military, Ambulance, and Hospital Service (the year of the diary entry is not given in the book, but it is almost certainly 1915):
The triage has been transferred from Moosch to Wilier; after leaving my men at the latter place, proceeded to the former.
And from the Washington Post of 14 June 1918:
Some “Triage” Hospitals.
Back of the nontransportable hospital near Montdidier that I described yesterday we have established, in that sector a considerable number of field hospitals[.] Some of these are “triage["] hospitals that is hospitals for meeting first aid emergencies, but equipped to do surgical work if necessary.
Essentially these hospitals are for the classification and distribution of wounded to the rear according to the character of the injuries.
Copyright 1997-2015, by David Wilton