The Collaborative International Dictionary of English v.0.48:

Niggle \Nig"gle\, v. t. [imp. & p. p. Niggled; p. pr. & vb. n.
   Niggling.] [Dim. of Prov. E. nig to clip money; cf. also
   Prov. E. nig a small piece.]
   To trifle with; to deceive; to mock. [Obs.] --Beau. & Fl.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Niggle \Nig"gle\, v. i.
   1. To trifle or play.
      [1913 Webster]

            Take heed, daughter,
            You niggle not with your conscience and religion.
                                                  --Massinger.
      [1913 Webster]

   2. To act or walk mincingly. [Prov. Eng.]
      [1913 Webster]

   3. To fret and snarl about trifles. [Prov. Eng.]
      [1913 Webster]

   4. (Chiefly Eng.)

   1. To move about restlessly or without result; to fidget.
      [Webster 1913 Suppl.]

   5. To be finicky or excessively critical; to potter; esp., to
      work with excessive care for trifling details, as in
      painting.
      [Webster 1913 Suppl.]

The Collaborative International Dictionary of English v.0.48:

Niggle \Nig"gle\, v. t.
   1. To use, spend, or do in a petty or trifling manner.
      [Webster 1913 Suppl.]

   2. To elaborate excessively, as in art.
      [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

niggle
    v 1: worry unnecessarily or excessively; "don't fuss too much
         over the grandchildren--they are quite big now" [syn:
         fuss, niggle, fret]
    2: argue over petty things; "Let's not quibble over pennies"
       [syn: quibble, niggle, pettifog, bicker, squabble,
       brabble]