quarto quartiparous • Quartodeciman · · · Info · Definitions · Synonyms · Characters · · quarto · · Text Latin · · Script 6 · · Length Definitions · · · (noun) the size of a book whose pages are made by folding a sheet of paper twice to form four leaves. Synonyms: 4to. · · Noun Definition 1 Synonyms · · · 4to · · Synonym 1 Characters · · a latin small letter a U+0061 o latin small letter o U+006F q latin small letter q U+0071 r latin small letter r U+0072 t latin small letter t U+0074 u latin small letter u U+0075