4to

Noun

quarto (countable and uncountable, plural quartos)

1. (paper) A size of paper (7.5"-10" x 10"-12.5" or 190-254 x 254-312 mm). Formed by folding and cutting one of several standard sizes of paper (15"-20" x 20"-25" or 381-508 x 508-635 mm) twice to form 4 leaves (eight sides).
   1. (UK, paper) Quarto writing paper (10 inches x 8 inches)
2. A book size, corresponding to the paper size.
   • Beneath an old ebony table were two long carved oak chests. I lifted the lid of one, and at the top was a once-white surplice covered with dust, and beneath was a mass of tracts — Commonwealth Quartos, unbound — a prey to worms and decay.1880, William Blades, The Enemies of Books, page 40

   Synonyms:

   4to, 4º, Q