Definition of "12mo" [12mo]

• Abbreviation of duodecimo, a page size (5"-5.5" x 7.125"-7.5") (noun)
• A book size using duodecimo-sized pages. (noun)

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• "A copy of this edition, described as 12mo, was listed under No. 1182 in the Hornby Castle Sale, 1930. 289"
• "Histoire Genealogique des Tatars (a Leyde, 1726, in 12mo., 2 tomes) was translated by the Swedish prisoners in Siberia from the Mogul"
• "Frederic Gronovius and Noodt, both translated, with valuable notes, by Barbeyrac, 2 vols. in 12mo."