What one same five letter Italian word can precede grosso, sottile, duro and relievo to denote a term in fresco painting. I have a word beginning with "g" which fits 3 of the 4,which is the best I can do.
Mezzo relievo is a term used in sculpture so mezzo is not correct.
The term gesso relief is not too difficult to find in english texts so presumably the italian translation is gesso relievo. ...just not to be found (easily) on the internet.
Gesso seems to be a word more specifically used for fresco painting, in any case.