# What does the "Roman" numeral Ɔ represent?

It's conceivable that the numeral Ɔ and letters it combines with are a mediaeval conceit rather than truly Roman — hopefully this is still on topic. I'm trying to decipher the publication date of a book published in Antwerp which is written as

CIƆ. ICƆ. XVII.

The last part is fairly obviously 17, and as it's a printed book it could even be 1517, since etching and moveable type had been invented. The peculiar character combinations bear a superficial similarity to M and D: is that what they represent?

The book is riddled with misprints, which would also point to a fairly early date for moveable type. If IƆ is supposed to be D, it would be reasonable for ICƆ to be a misprint, but the presence of C in that group is another point of confusion.

There is a related question, but that doesn't really explain CIƆ and certainly not ICƆ.

• I guess ICƆ is misprint for IƆC (= DC = 600) in which case the year would be 1617. More about the Ɔ at en.wikipedia.org/wiki/Roman_numerals#Apostrophus Commented Oct 10, 2020 at 13:32
• Scopro per caso a distanza di tre anni questo forum e vi descrivo il mio caso. Sono giunto in possesso di una copia in latino delle "Gaii Institutiones" curate da Edward Bucking e pubblicate come quinta edizione a Lipsia nell'anno 1866. Ebbene, in cifre romane si parla di "A. CIƆ IƆCCCLXVI". Mi pare quindi evidente, fatto salvo che le cifre CCCLXVI significano 366 (CCC=300 e LXVI=66), che CIƆ IƆ altro non siano che una forma errata/medievaleggiante/stilizzata di M D: da qui CIƆ IƆCCCLXVI= MDCCCLXVI= 1866. Commented Mar 7, 2023 at 23:52