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]

Moby Thesaurus II by Grady Ward, 1.0:

119 Moby Thesaurus words for "tittle":
   ace, atom, birthmark, bit, blaze, blemish, blotch, brand,
   caste mark, check, checkmark, cicatrix, crumb, cut, dab, dapple,
   diacritical mark, discoloration, dole, dot, dram, dribble, driblet,
   drop, droplet, dwarf, earmark, end stop, engraving, farthing,
   fleck, flick, flyspeck, fragment, freckle, gash, gnat, gobbet,
   grain, granule, graving, groat, hack, hair, handful, iota, jot,
   lentigo, little, little bit, lota, macula, mark, marking, microbe,
   microorganism, midge, minim, minimum, minutia, minutiae, mite,
   modicum, mole, molecule, mote, mottle, nevus, nick, notch,
   nutshell, ounce, particle, patch, pebble, pinch, pinhead, pinpoint,
   pittance, point, polka dot, prick, punctuation, punctuation marks,
   puncture, reference, reference mark, scar, scarification, score,
   scotch, scrap, scratch, scratching, scruple, smidgen, smitch, snip,
   snippet, speck, speckle, splash, splotch, spoonful, spot, stain,
   stigma, stop, strawberry mark, tattoo, tattoo mark, thimbleful,
   tick, tiny bit, trifling amount, trivia, vanishing point,
   watermark, whit



Easton's 1897 Bible Dictionary:

Tittle
   a point, (Matt. 5:18; Luke 16:17), the minute point or stroke
   added to some letters of the Hebrew alphabet to distinguish them
   from others which they resemble; hence, the very least point.