Definition of "undated" []

• Not marked with or showing a date: an undated letter; an undated portrait. (adjective)
• Being such as to have long-lasting appeal without ever going out of style: a classic, undated dress. (adjective)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "It's an interesting, unpretentious, receptive personal literary experiment (pdf excerpt here), and Halliday's surprise takeaway is how remarkably, vibrantly "undated" most of the contents of Hudson Review summer '63 are."
• "There are several copies listed in both places as "undated" and "reprints" -- I'm avoiding these, since while it's quite likely that they might be clearable, I'm not taking risks on this search."
• "The new set of booklets are undated, meaning they can be used every year."