Is “Octodecimo” a Scrabble word?
Yes
OCTODECIMO
Valid in at least one Scrabble dictionary
Valid in these dictionaries
SOWPODS / CSW
Scrabble UK & International
TWL / NWL
Scrabble North America
Large English Dictionary
General English word list
Meaning of Octodecimo
noun
1.A size of a sheet of paper resulting from folding and cutting a sheet of paper into eighteenths (3.5"-4.5" x 4.9"-5.9").
2.A book consisting of pages of that size.
Synonyms: 18mo, 18º, T, eighteenmo, 18mo, 18º