in-quarton.
Etymology: < phrase in quarto (see quarto n. and adj.); compare French in-quarto.Previous versions of the OED give the stress as: in-ˈquarto.
rare.
society > communication > book > kind of book > size of book > [noun] > quarto volume
1865 4 July 5/1 To form a thin in-quarto.
This entry has not yet been fully updated (first published 1900; most recently modified version published online June 2021).