Italian term for the edge or line formed by the meeting of two surfaces.
Spigolo is the Italian term for the line formed by the intersection of two surfaces or faces, particularly where the meeting creates a projecting or acute edge.
In sculpture and stonework, the word is useful for discussing the crisp meeting of planes, the treatment of edges, and the care required to prevent an edge from being unintentionally softened during finishing.
English equivalent: arris.
Etymology
From Latin spiculum, a diminutive of spica, meaning 'ear of grain' or 'point.' The underlying sense is of a point, sharp projection, or edge.
Sculptor Notes
A useful bottega term when asking about clean edges in marble. The distinction becomes especially important during rasping, abrasive finishing, and polishing, when an otherwise precise edge can easily be softened. Cross-reference: Arris; Spigolo vivo.
References
https://www.treccani.it/vocabolario/spigolo/