A carving technique in which a design or image is cut below the surrounding surface rather than projecting outward from it.
Intaglio is a sculptural technique in which a design is sunk below the surrounding surface by carving or incising. It is the inverse of projecting relief and has long been associated with engraved gems, seals, hardstone carving, and other small-scale works requiring precise recessed imagery.
In broader art usage, intaglio can also refer to printmaking processes in which ink is held in recessed lines or areas. Within a sculpture lexicon, the term should be understood primarily as the carving of a sunken design.
Etymology
Italian intaglio, “engraving” or “carving,” from intagliare, “to carve or cut into.”
Sculptor Notes
Intaglio depends on the control of recessed edges and depths rather than projecting masses. In hard stone and gems, very small changes in depth can strongly affect the image, particularly when the work is used to make an impression in wax or another soft material.
References
https://www.getty.edu/vow/AATFullDisplay?subjectid=300186231