ost·mark (ôst?märk?, ?st?-)n. A former unit of currency in East Germany worth 100 pfennigs.[German : Ost, east (from Middle High German ?st, ?sten, from Old High German ?stan; see aus- in Indo-European roots) + Mark, mark (from Middle High German marke, marc; see mark2).]American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.Ostmark (??st?m??k; German ??stmark) n (Currencies) (formerly) the standard monetary unit of East Germany, divided into 100 pfennigs[German, literally: east mark]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014ost?mark (??st?m?rk, ??st-) n. the former basic monetary unit of East Germany: replaced by the West German mark in 1990. [1945?50;