The Collaborative International Dictionary of English v.0.48:

Hestern \Hes"tern\, Hesternal \Hes*ter"nal\, a. [L. hesternus;
   akin to heri yesterday.]
   Pertaining to yesterday. [Obs.] See Yester, a. --Ld.
   Lytton.
   [1913 Webster]