Coelanaglyphic

The varieties of relief are still further distinguished as […] cavo-rilievo, hollow relief, also called intaglio rilevato, or cœlanaglyphic sculpture, an Egyptian form of relief obtained by cutting a furrow with sloping sides around a figure previously outlined on a stone surface, leaving the highest parts of the finished work on a level with the original surface-plane.

Source: wiktionary

The Egyptian column, covered with painted figures from top to bottom, and in many cases wrought with cœlanaglyphic sculptures which are then elaborately treated in colour, was more in itself, shaft and capital taken together, than any column of the Greeks. [Footnote 12: Cœlanaglyphic; also concavo-convex or cavo-rilievo: denoting relief-sculpture which is in a sunken panel, which it fills completely, leaving no background. It is as if a groove were cut around the sculptured figure, which is then wrought into complete modelling; while the background is not cut away, lowered, or abated, as in ordinary relief[…]]

Source: wiktionary

A type of incised relief employed largely by the Egyptians for architectural ornament is the inverse bas-relief, also referred to as coelanaglyphic or Egyptian relief. […] It is an intaglio form in which the figures do not project from the wall, but are cut into it, as on the pylon of the Temple at Philae (Temple of Isis). In this from of intaglio relief, the figures are outlined by means of grooves or furrows cut around the forms. The highest points or portions of the completed work are on a level with the original surface plane.

Source: wiktionary

A relief is generally a sculptured surface raised from a background, although the ancient Egyptians, for instance, also devised intaglio relief—that is, sculptured relief within a bordered boundary, referred to as coelanaglyphic relief. The basic characteristic of relief that distinguishes it from sculpture in the round is its physical dependence on some kind of background or matrix.

Source: wiktionary