The Collaborative International Dictionary of English v.0.48:

Luke \Luke\ (l[=u]k), a. [Prob. fr. lew, perh. influenced by AS.
   wl[ae]c warm, lukewarm, remiss. Cf. Lew.]
   Moderately warm; not hot; tepid; lukewarm. -- Luke"ness, n.
   [Obs.]
   [1913 Webster]

         Nine penn'orth o'brandy and water luke.  --Dickens.
   [1913 Webster]