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sixty-fourmo

[siks-tee-fawr-moh, -fohr-]
noun, plural six·ty-four·mos.
  1. a book size (about 2 × 3 inches; 5 × 7 cm) determined by printing on sheets folded to form 64 leaves or 128 pages.
  2. a book of this size. Symbol: 64mo, 64°
adjective
  1. printed, folded, or bound in sixty-fourmo.

Origin of sixty-fourmo

sixty-four + -mo
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for sixty-fourmo

sixty-fourmo

noun plural -mos
  1. a book size resulting from folding a sheet of paper into 64 leaves or 128 pages, each one sixty-fourth the size of the sheetOften written: 64mo, 64°
  2. a book of this size
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012