WordWeb Online

1. (informal) small and of little importance
   "a dispute over niggling details"
   - fiddling, footling, lilliputian, little, piddling, piffling, petty, picayune [N. Amer], trivial

1. Worry unnecessarily or excessively
   - fuss, fret
    
2. Argue over petty things
   - quibble, pettifog, bicker, squabble, brabble

See also: niggler, unimportant

Type of: argue, contend, debate, fence, worry

Encyclopedia: Niggle