Source : Webster's Revised Unabridged Dictionary (1913)

Undated \Un"da*ted\, a. [L. undatus, p. p. of undare to rise in
   waves, to wave, to undulate, fr. unda a wave. See
   {Undulate}.] (Bot.)
   Rising and falling in waves toward the margin, as a leaf;
   waved.

Undated \Un*dat"ed\, a. [Pref. un- + dated.]
   Not dated; having no date; of unknown age; as, an undated
   letter.

Source : WordNet®

undated
     adj : not bearing a date; "a dateless letter" [syn: {dateless}]