The Collaborative International Dictionary of English v.0.48:

Tittle \Tit"tle\, n. [OE. titel, titil, apparently a dim. of
   tit, in the sense of small; cf. G. t["u]ttel a tittle, dim.
   of OHG. tutta teat. Perhaps, however, the same word as title,
   n.]
   A particle; a minute part; a jot; an iota.
   [1913 Webster]

         It is easier for heaven and earth to pass, than one
         tittle of the law to fail.               --Luke xvi.
                                                  17.
   [1913 Webster]

         Every tittle of this prophecy is most exactly verified.
                                                  --South.
   [1913 Webster]

WordNet (r) 3.0 (2006):

tittle
    n 1: a tiny or scarcely detectable amount [syn: shred,
         scintilla, whit, iota, tittle, smidgen,
         smidgeon, smidgin, smidge]