'Printer's ream' definitions:

Definition of 'Printer's ream'

From: GCIDE

Ream \Ream\, n. [OE. reme, OF. rayme, F. rame (cf. Sp. resma), fr. Ar. rizma a bundle, especially of paper.] A bundle, package, or quantity of paper, usually consisting of twenty quires or 480 sheets. [1913 Webster]
Printer's ream, twenty-one and a half quires. [Eng.] A common practice is now to count five hundred sheets to the ream. --Knight. [1913 Webster]