Definition of eighteenmo in English:

eighteenmo

nouneighteenmos

another term for octodecimo
‘Comparing his list of conger members with the Tillotson imprints shows that the conger also produced the folios of 1728 and the eighteenmo of 1748.’
another term for octodecimo
‘On the basis of the distribution of the watermarks the volume may be identified as an eighteenmo.’

Pronunciation

eighteenmo

/eɪˈtiːnməʊ/