[1] : The Collaborative International Dictionary of English v.0.48

datable \dat"able\, a.
   that may be dated; having a known or ascertainable date.
   "datable almost to a year." --the century.

   syn: dateable. 1913 webster

[2] : WordNet (r) 2.0

datable
     adj : that can be given a date; "a concrete and datable
           happening"- c.w.shumaker syn: dateable ant: undatable
see also:
dateable undatable 

Datable >> D Words
Datable, definition of term: Datable
datable_pag1.html