Glossary Term Definition
A unit of typographic measurement equal to 12 Didot points, approximately 4.52 mm, used in continental European typography.
Definition
A unit of typographic measurement equal to 12 Didot points, approximately 4.52 mm. The cicero is the continental European counterpart of the Anglo-American pica. It takes its name from the edition of Cicero's De Oratore printed by Sweynheym and Pannartz at Subiaco in 1465.
Source
No access — Robert Bringhurst — p. 323:
A unit of typographic measurement equal to 12 Didot points.