The Collaborative International Dictionary of English v.0.48:

Piddle \Pid"dle\, v. i. [imp. & p. p. Piddled; p. pr. & vb. n.
   Piddling.] [Cf. dial. Sw. pittla to keep picking at, Sw.
   peta to pick.]
   1. To deal in trifles; to concern one's self with trivial
      matters rather than with those that are important.
      --Ascham.
      [1913 Webster]

   2. To be squeamishly nice about one's food. --Swift.
      [1913 Webster]

   3. To urinate; -- child's word.
      [1913 Webster]

WordNet (r) 3.0 (2006):

piddle
    n 1: liquid excretory product; "there was blood in his urine";
         "the child had to make water" [syn: urine, piss, pee,
         piddle, weewee, water]
    v 1: waste time; spend one's time idly or inefficiently [syn:
         piddle, wanton, wanton away, piddle away, trifle]
    2: eliminate urine; "Again, the cat had made on the expensive
       rug" [syn: make, urinate, piddle, puddle,
       micturate, piss, pee, pee-pee, make water, relieve
       oneself, take a leak, spend a penny, wee, wee-wee,
       pass water]

Moby Thesaurus II by Grady Ward, 1.0:

67 Moby Thesaurus words for "piddle":
   beguile the time, burn daylight, consume time, coquet, dabble,
   dally, dawdle, diddle, dillydally, doodle, fiddle, fiddle with,
   fiddle-faddle, fidget with, finger with, flirt, fool, fool around,
   fool with, footle, fribble, fritter away time, frivol,
   horse around, idle, jerk off, kid around, kill time, lag, linger,
   loiter, lollygag, lose time, make water, mess around, micturition,
   monkey, monkey around, number one, pass the time, pee, pee-pee,
   pish, piss, play, play around, play with, poke, potter, pump bilge,
   putter, smatter, spend a penny, stale, tinker, toy, toy with,
   trifle, twiddle, urea, urinate, urination, urine, waste time,
   water, wee-wee, wet