The Collaborative International Dictionary of English v.0.48:

Dime \Dime\ (d[imac]m), n. [F. d[^i]me tithe, OF. disme, fr. L.
   decimus the tenth, fr. decem ten. See Decimal.]
   A silver coin of the United States, of the value of ten
   cents; the tenth of a dollar.
   [1913 Webster]

   Dime novel, a novel, commonly sensational and trashy, which
      is sold for a dime, or ten cents; -- they were popular
      from ca. 1850 to ca. 1920. Sometimes the term is still
      applied to any novel of the type, though the price has
      greatly increased.
      [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

dime novel
    n 1: a melodramatic paperback novel [syn: dime novel, penny
         dreadful]