Page "Anointing of the Sick" Paragraph 3

Extreme Unction was the usual name for the sacrament in the West from the late twelfth century until 1972, and was thus used at the Council of Trent and in the 1913 Catholic Encyclopedia.

Peter Lombard ( died 1160 ) is the first writer known to have used the term, which did not become the usual name in the West till towards the end of the twelfth century, and never became current in the East.

The word " extreme " ( final ) indicated either that it was the last of the sacramental unctions ( after the anointings at Baptism, Confirmation and, if received, Holy Orders ) or because at that time it was normally administered only when a patient was in extremis.